Methods and apparatus for automatic TV on/off detection

ABSTRACT

Methods and apparatus are disclosed to determine a power state of a device. An example apparatus includes a chart generator to determine respective counts for a plurality of measurements during a calibration period, the measurements indicative of an amount of power drawn by the device, the counts indicating respective numbers of times the respective measurements were detected. The example apparatus also includes a calculator to identify a first threshold based on at least one of the counts, and determine a second threshold. The example apparatus also includes a comparator to compare a measurement to the first threshold and to the second threshold, and a state detector to store an indication that the device is in an indeterminate state if the measurement is greater than the first threshold and less than the second threshold.

RELATED APPLICATION

This patent is a continuation of U.S. patent application Ser. No.15/633,394, entitled “Methods and Apparatus for Automatic TV ON/OFFDetection,” and filed Jun. 26, 2017, which is a continuation of U.S.patent application Ser. No. 13/473,320, entitled “Methods and Apparatusfor Automatic TV ON/OFF Detection,” and filed May 16, 2012, which claimspriority to U.S. Provisional Application Ser. No. 61/600,894, entitled“Methods and Apparatus for Automatic TV ON/OFF Detection without ManualCalibration Using the Current or Power Draw of the TV,” and filed onFeb. 20, 2012. U.S. patent application Ser. No. 15/633,394, U.S. patentapplication Ser. No. 13/473,320, and U.S. Provisional Application Ser.No. 61/600,894 are hereby incorporated herein by reference in theirentireties.

FIELD OF THE DISCLOSURE

This disclosure relates generally to audience measurement and, moreparticularly, to methods and apparatus for automatic television ON/OFFdetection.

BACKGROUND

Audience measurement of media, such as television and/or radio programs,is typically carried out by monitoring media exposure of panelists thatare statistically selected to represent particular demographic groups.Audience measurement companies, such as The Nielsen Company (US), LLC,enroll households and persons to participate in measurement panels. Byenrolling in these measurement panels, households and persons agree toallow the corresponding audience measurement company to monitor theirexposure to information presentations, such as media output via atelevision, a radio, a computer, etc. Using various statistical methods,the collected media exposure data is processed to determine the sizeand/or demographic composition of the audience(s) for media program(s)of interest. The audience size and/or demographic information isvaluable to, for example, advertisers, broadcasters, content providers,manufacturers, retailers, product developers, etc. For example, audiencesize and/or demographic information is a factor in the placement ofadvertisements, in valuing commercial time slots during particularprograms and/or generating ratings for piece(s) of media.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of an example system including an examplemonitoring system constructed in accordance with the teachings of thisdisclosure.

FIG. 2 is a block diagram of an example implementation of the examplepower supply of FIG. 1.

FIG. 3 is a block diagram of a first example implementation of theexample meter of FIG. 1.

FIG. 4 is a block diagram of an example implementation of the examplecalibrator of FIG. 3.

FIG. 5A illustrates a first example list generated by the example powerlogger of FIG. 4.

FIG. 5B illustrates a second example list generated by the example powerlogger of FIG. 4.

FIG. 6 is a block diagram of an example implementation of the examplethresholds generator of FIG. 4.

FIG. 7A illustrates an example comparison chart generated by the examplechart generator of FIG. 6.

FIG. 7B illustrates an example power chart generated by the examplechart generator of FIG. 6.

FIG. 8 illustrates an example chart used by the example OFF thresholdcalculator of FIG. 6.

FIG. 9 illustrates an example chart used by the example ON thresholdcalculator of FIG. 6.

FIG. 10 is a block diagram of an example implementation of the examplestate detector of FIG. 3.

FIG. 11 illustrates an example graph representative of powermeasurements received by the example meter of FIGS. 1 and/or 3.

FIG. 12 is a flowchart representative of example machine readableinstructions that may be executed to implement the example meter ofFIGS. 1 and/or 3.

FIG. 13 is a flowchart representative of example machine readableinstructions that may be executed to implement the example calibrator ofFIGS. 3, 4 and/or 6.

FIG. 14 is a block diagram of a second example implementation of theexample meter of FIG. 1.

FIG. 15 is a flowchart representative of example machine readableinstructions that may be executed to implement the second example meterof FIG. 14.

FIG. 16 is a block diagram of an example processing platform capable ofexecuting the example machine readable instructions of FIGS. 12, 13 and15 to implement the example meter of FIGS. 1, 3 and/or 14.

DETAILED DESCRIPTION

Television ON/OFF detection is useful in metering media exposure. Forexample, in the television monitoring context, the data collected viaON/OFF detection is used to calculate Households Using Television(“HUT”) and People Using Television (“PUT”) data. Knowing whether aninformation presentation device, such as a television (TV), is ON or OFFis useful for generating exposure statistics, such as HUT and PUT data,because media is often tuned through a device other than thepresentation device (e.g., through a set-top box (STB)). In suchinstances, media may be tuned by the STB but not actually presented onan information presentation device because the information presentationdevice is turned OFF. Thus, crediting the tuned data as presented on theinformation presentation device (e.g., a TV, a radio, etc.) based solelyon tuning information of the STB can result in inaccurate exposure data.Knowledge of the ON/OFF state of an information presentation device isalso useful for conserving energy. For example, a meter tasked withmonitoring a television can be powered down when the television isdetermined to be in an OFF state, thereby conserving energy when novalid and/or useful data (with respect to the meter) is available forcollection.

An amount of consumed electrical current is sometimes used as anindicator for determining whether an information presentation device,such as a television, was in an ON state or an OFF state. For example, acurrent sensor (e.g., a Current Threshold Sensor Attachment (“CTSA”),CTSA2, or CTSA3) deployed in connection with a power apparatus (e.g.,cord) of a television detects an amount of current drawn by thetelevision from, for example, a power source such as a wall outlet. Sucha current sensor is typically manually calibrated by, for example, afield representative associated with the corresponding meter.Calibrating the current sensor includes setting a threshold. Thetelevision is expected to draw current above the threshold when in an ONstate, and to draw current below the threshold when in an OFF state.Thus, current readings taken by the sensor are compared to the thresholdto determine whether the television is in an ON state or an OFF state

A straightforward threshold setting (e.g., a single ON/OFF threshold) ispractical when used in connection with, for example, cathode raytelevisions (“CRTVs”), which have relatively few options for the stateof the television. CRTVs generally have OFF, ON, and Input or BlackScreen states. When in the ON state or the Input state, such televisionsdraw considerably more power (e.g., current and/or voltage) than when inthe OFF state. Therefore, threshold calibration for CRTVs is relativelystraightforward.

However, more advanced televisions (e.g., smart televisions) are morecomplex and operate in a greater number of states. For example, smarttelevisions include options such as Economy Mode, Picture Off, Fastversus Slow ON, 3D viewing, Internet streaming, ON, OFF, Input, BlackScreen, etc. In some instances, televisions enter a hibernation state toconserve energy in which the television draws more power than when inthe OFF state, but less power than when in the ON state. In someinstances, Fast ON states, Fast OFF states, Slow OFF states, and Slow ONstates cause the television to gradually transition from an ON state toan OFF state and vice-a-versa. Such televisions draw an intermediateamount of current during the transitions. Additional and/or alternativecurrent draw scenarios and states are possible with present and futuretelevisions.

The wide range of settings and options available on such televisionscorresponds to a similarly wide range of possible power draws. The widerange of possible power draws for such a television makes automaticON/OFF state detection less straightforward than with, for example,conventional CRTVs. For example, when a wide range of possible powerdraws exists, manual calibration process(s) are more time-consuming(e.g., require a field representative up to 10 hours to calibrate) andrequire complex calculations to set threshold(s). Further, more complextelevisions (with respect to a number of possible power draw levels)give rise to the possibility of needing re-calibration if, for example,a setting is changed after an initial calibration (e.g., by a userand/or a member of a media exposure panel). For example, an initialcalibration of a threshold may be based on the television being in astandard OFF state when not presenting media. However, a user maysubsequently change a setting or mode of the television (e.g., a faststart mode) that causes the television to draw more power than thestandard OFF state when not presenting media. In such instances, theinitial calibration may lead to inaccurate readings, measurements and/ormonitoring of media exposure.

Example methods, apparatus, and/or articles of manufacture disclosedherein enable accurate and sustainable ON/OFF detection for informationpresentation devices, such as televisions. Examples disclosed herein areparticularly useful in connection with information presentation devicesthat operate in a plurality of different states and/or modes that causethe information presentation devices to draw different amount(s) ofpower.

Examples disclosed herein provide meters tasked with monitoring aninformation presentation device with multiple thresholds that are setaccording to an on-going calibration technique. As described in detailbelow, example calibration techniques disclosed herein include aninitial calibration of thresholds upon, for example, installation of thecorresponding meter. To enable the meter to adapt to changes associatedwith the information presentation device (e.g., changes in settingsand/or modes of the television), example calibration techniquesdisclosed herein re-calibrate the meter at intervals (e.g., each day).Moreover, example calibration techniques disclosed herein enable metersto avoid basing a threshold calculation on outlier conditions and/ordetections.

Further, example state detection techniques disclosed herein enablemeters to detect a state of the corresponding information presentationdevices using detected power when the information presentation deviceshave wide and/or complex ranges of power characteristics. In otherwords, examples disclosed herein enable meters to accurately determine astate of an information presentation device that operates in a widevariety of states. As described in greater detail below, examplesdisclosed herein analyze current and previously detected power states ofan information presentation device to identify states of the informationpresentation devices.

FIG. 1 illustrates an example monitoring system 100 constructed inaccordance with teachings of the present disclosure to monitor a stateof an information presentation device 102. In the illustrated example,the information presentation device 102 is a television implemented at amonitored site (e.g., a household), such as any of the monitored sites94-98. However, the example monitoring system 100 can be implemented inconnection with additional and/or alternative types of informationpresentation device(s) operating in a plurality of states. The exampleinformation presentation device 102 of FIG. 1 is powered by a powersource 101 (e.g., a wall outlet or any other type of commercial power)via a power supply 111. The example monitoring system 100 of FIG. 1 isin communication with a central facility 160 via a network 150.

The example network 150 of FIG. 1 communicates data from the monitoredsite 98 to the example central facility 160 and/or a remote storagelocation associated with the central facility 160. The example network150 may be implemented using any type of public and/or private networksuch as, for example, the Internet, a telephone network (e.g., the PlainOld Telephone System), a cellular network, a local area network (“LAN”),a cable network and/or a wireless network.

The example central facility 160 of the illustrated example collectsand/or stores, for example, television ON and OFF determinations, mediaexposure data, media monitoring data and/or demographic informationcollected by monitoring systems, such as the example monitoring system100 of FIG. 1, associated with respective ones of a plurality ofmonitored sites (e.g., multiple panelist houses). The example centralfacility 160 may be, for example, a facility associated with The NielsenCompany (US), LLC or any affiliate of The Nielsen Company (US), LLC. Theexample central facility 160 of FIG. 1 includes a server and a databasewhich may be implemented using any suitable processor, memory and/ordata storage such as, for example, the processor platform 1612 shown inFIG. 16.

The example monitoring system 100 of FIG. 1 includes a meter 120 and asensor 110 implemented in connection with the example power supply 111.In the example of FIG. 1, the power supply 111 is coupled to the powersource 101 via, for example, a three pronged power plug. The informationpresentation device 102 is coupled to the example power supply 111 viaany suitable connector such as, for example, a three pronged power plug.The example power supply 111 transfers power from the power source 101to the information presentation device 102 in accordance with the powerdemand of the information presentation device 102. As described ingreater detail below, the example information presentation device 102 ofFIG. 1 is capable of being in any of a plurality of states. Theinformation presentation device 102 draws different amounts of powerfrom the power source 101 via the power supply 111 depending on whichone of the states the information presentation device 102 is operating.

The example sensor 110 of FIG. 1 monitors (e.g., senses) the amount ofpower drawn from the power source 101 by the example informationpresentation device 102 via the power supply 111. The example sensor 110of FIG. 1 monitors an amount of current drawn by the informationpresentation device 102. However, additional and/or alternativemeasurements can be utilized by the example sensor 110 of FIG. 1. Forexample, the sensor 110 can measure a current and/or a combination ofcurrent and voltage to determine an amount of power being drawn by theinformation presentation device 102. The example sensor 110 measures thepower drawn by the information presentation device 102 withoutdisturbing operation of the example information presentation device 102.

In the example of FIG. 1, an output from the sensor 110 is communicatedto the example meter 120. The example sensor 110 of FIG. 1 is incommunication with the example meter 120 via, for example, a UniversalSerial Bus (USB) cable and/or any other suitable type of connector. Insome examples, the sensor 110 and meter 120 are additionally oralternatively placed in communication wirelessly (e.g., via Wi-Fi,Bluetooth, etc.). In the illustrated example, the sensor 110communicates a value representative of a power level drawn by theinformation presentation device 102. As described below in connectionwith FIG. 2, the example sensor 110 outputs a digital number convertedfrom an analog signal which corresponds to (e.g., is representative of,is proportional to, etc.) the wattage or power level drawn by theexample information presentation device 102. The digital number outputfrom the example sensor 110 of FIG. 1 is communicated to the examplemeter 120 via, for example, USB protocol. However, any other past,present, or future wired or wireless communication protocol mayalternatively be employed.

In the illustrated example, the example meter 120 utilizes the receivedoutput from the example sensor 110 to calibrate one or more thresholdsand to determine a present power state (e.g. ON or OFF) of theinformation presentation device based on the threshold(s). In someexamples, the meter 120 processes the power state determination locally(e.g., via a processor such as the processor 1612 of FIG. 16 carried bythe meter 120). In other examples, the meter 120 transfers the data onwhich the determination is based to the example central facility 160(e.g., via the example network 150) for processing.

As described in detail below in connection with FIGS. 3-9 and 12-15, thethreshold(s) on which the example meter 120 bases the statedeterminations are calculated by the example meter 120 of FIG. 1 basedon learned behavior of the information presentation device 102. Inparticular, the example meter 120 of FIG. 1 logs outputs from theexample sensor 110 during an initial calibration period to identify apower draw of the example information presentation device 102 while theinformation presentation device is in the OFF state. An initial set ofthresholds (e.g., an OFF threshold and an ON threshold) is thengenerated based on the identified power draw. Further, the example meter120 of FIG. 1 repeatedly recalibrates the thresholds based on continuedmeasurements taken by the sensor 110 and one or more assumptionsdescribed in detail below.

FIG. 2 is a block diagram of an example implementation of the examplepower supply 111 of FIG. 1. In the illustrated example, the sensor 110is used to measure the power (e.g., current and/or voltage) drawn by theexample information presentation device 102 of FIG. 1. The sensor 110 ofthe illustrated example monitors the power drawn by the exampleinformation presentation device 102 from the example power source 101and outputs a corresponding value to the example meter 120. To do so,the example power supply 111 includes a pass through port 211, an outputinterface 216, and the sensor 110. In the illustrated example, thesensor 110 includes a current detector 217 and an analog-to-digitalconverter 215.

The example pass through port 211 of FIG. 2 receives current (e.g., ACcurrent) from the power source 101 and provides the current to theexample information presentation device 102 of FIG. 1. In some examples,the power supply 111 includes a filter to eliminate noise from theoutput of the sensor 110. The current passing through the example passthrough port 211 of FIG. 2 is monitored by the example current detector217. The example current detector 217 may be any type of sensor able tomeasure the current drawn by the information presentation device 102(e.g., a Hall Effect Sensor).

In the illustrated example, the current detector 217 conveys a readingand/or measurement to the example analog-to-digital converter 215. Theexample analog-to-digital converter 215 outputs a digital voltageproportional to the analog voltage received from the example sensor 110.In the example of FIG. 2, the analog-to-digital converter 215 includes aPIC18 microprocessor. The example analog-to-digital converter 215translates the voltage received from the example current detector 217into a digital value. The reading and/or measurement taken by theexample sensor 110 is then output to the example meter 120 via theoutput interface 216 (e.g., a USB port). The data is communicated to themeter 120 periodically (e.g., in response to a clock), aperiodically(e.g., in response to one or more events or conditions) and/orcontinuously. In some examples, the output of the sensor 110 is storedin local memory in addition to and/or prior to outputting the value tothe meter 120. In some examples, this digital value is 12-bits long(e.g., to provide representation for a range between 0 and 4095).

Thus, the digital value output by the example sensor 110 of theillustrated example is representative of (e.g., proportional to) thecurrent drawn by the monitored information presentation device 102. Insome examples, the digital value has no units but is interpreted as arepresentation of the average current drawn by the monitored informationpresentation device 102 from the power source 101 (e.g., in Amps). Asthe output of the example sensor 110 of FIG. 2 corresponds to thecurrent, and power is proportional to current (P=I*V), the output of thesensor 110 likewise corresponds (e.g., is proportional) to the wattagedrawn by the monitored information presentation device 102. Therefore,the output of the example sensor 110 may be referred to as a powerreference or value (e.g., wattage).

While an example manner of implementing the power supply 111 of FIG. 1has been illustrated in FIG. 2, one or more of the elements, processes,and/or devices illustrated in FIG. 2 may be combined, divided,re-arranged, omitted, and/or implemented in any other way. Further, theexample current detector 217, the example analog-to-digital converter215 and/or, more generally, the example sensor 110 of FIG. 2 may beimplemented by hardware, software, firmware and/or any combination ofhardware, software and/or firmware. Thus, for example, any of theexample current detector 217, the example analog-to-digital converter215 and/or, more generally, the example sensor 110 of FIG. 2 could beimplemented by one or more circuit(s), programmable processor(s),application specific integrated circuit(s) (ASIC(s)), programmable logicdevice(s) (PLD(s)) and/or field programmable logic device(s) (FPLD(s)),etc. When any of the apparatus or system claims of this patent are readto cover a purely software and/or firmware implementation, at least oneof the example current detector 217, the example analog-to-digitalconverter 215 and/or the sensor 110 are hereby expressly defined toinclude a tangible computer readable storage medium such as a memory,DVD, CD, Blu-ray, etc. storing the software and/or firmware. Furtherstill, the example power supply 111 of FIG. 2 may include one or moreelements, processes and/or devices in addition to, or instead of, thoseillustrated in FIG. 2, and/or may include more than one of any or all ofthe illustrated elements, processes and devices.

FIG. 3 illustrates an example implementation of the example meter 120 ofFIG. 1. In the illustrated example, the meter 120 is used to determinethe power state (e.g., ON, OFF) of an information presentation devicesuch as, for example, the example information presentation device 102 ofFIG. 1. As described above, the state of the information presentationdevice 102 is used (e.g., by an audience measurement entity) to generatestatistics related to media exposure at, for example, the monitoredsites 94-98. The example meter 120 of FIG. 3 receives a powermeasurement (e.g., a digital value representative of a power level) fromthe sensor 110 of FIGS. 1 and/or 2 via an input interface 301. Theexample input interface 301 of FIG. 3 is implemented by a USB port.However, the example meter 120 can utilize any suitable interface. Theinput interface 301 transmits the received power measurement to acalibrator 320 and a state detector 370. The example state detector 370of FIG. 3 determines the state of the information presentation device102 (e.g., ON, OFF) based on a plurality of thresholds generated by thecalibrator 320 of the example meter 120. As described in detail below inconnection with FIG. 4, the example calibrator 320 repeatedly (e.g.,periodically, aperiodically, according to a schedule, etc.) calibratesthe meter 120 by identifying and/or adjusting the thresholds on whichthe state determinations of the example state detector 370 are based. Tocalculate and/or adjust the thresholds, the example calibrator 320generates a power chart using the values received from the sensor 110 ofFIGS. 1 and/or 2. In the example of FIG. 3, the calibrator 320 storesthe power chart in a chart storage device 392. Further, the thresholdsgenerated by the calibrator 320 using the generated chart of the chartstorage device 392 are stored in a threshold storage device 394.Generation of the power charts and the thresholds are described indetail below in connection with FIGS. 4-9.

The example state detector 370 compares the received currentmeasurement, which is representative of an amount of power currentlydrawn by the information presentation device 102, to the thresholdsgenerated by the calibrator 320 to identify a state of the informationpresentation device 102. As the example state detector 370 determinesthe state of the information presentation device 102, the example statedetector 370 records the state determinations in a state ID storagedevice 396. The data of the state ID storage device 396 is transmitted(e.g., periodically, aperiodically, according to a schedule, etc.) tothe example central facility 160 of FIG. 1. Additionally and/oralternatively, the example state detector 370 conveys the detectedstates directly to the central facility 160 (e.g., without being storedin the local state ID storage device 396). The state determinations ofthe example state detector 370 are described below in connection withFIGS. 10 and 11.

The example calibrator 320 and the example state detector 370 of FIG. 3cooperate to enable the meter 120 to determine whether, for example, theinformation presentation device 102 is ON or OFF at a given time or fora given period of time based on repeatedly and automatically calibratedthresholds.

FIG. 4 illustrates an example implementation of the example calibrator320 of FIG. 3. In the illustrated example of FIG. 4, the calibrator 320includes a power logger 424, a thresholds generator 440 and a timelogger 422. The example time logger 422 maintains timing information tocontrol different calibration modes of the example calibrator 320. Forexample, the calibrator 320 of FIG. 4 includes a learning mode and arecalibration mode. When the example calibrator 320 of FIG. 4 is inlearning mode, the duration of the corresponding calibration period is arelatively short period of time (e.g., five minutes). In the illustratedexample, the learning mode corresponds to an initial period ofcalibration that occurs when, for example, the meter 120 is firstinstalled at the monitored site 98 of FIG. 1. In some examples, themeter 120 enters the learning mode when, for example, the meter 120 isfirst installed, is reset and/or is undergoing an update (e.g., asoftware update). The recalibration mode has a longer duration than thelearning mode. For example, while the learning mode of the illustratedexample lasts for five minutes, the recalibration mode may be of anyother duration, (e.g., twenty-four hours). As described below, therecalibration mode enables the meter 120 to continue to base itsdetermination on accurate thresholds by avoiding scenarios in whichchanges in the operation and/or mode of the television skew the resultsof the comparison performed by the state detector 370. The example timelogger 422 of FIG. 4 stores the calibration period duration value anddetermines when instances of, for example, the recalibration mode haveended (e.g., to indicate that a new period can begin). The example timelogger 422 communicates an indicator indicative of an expiration of acalibration period to the example thresholds generator 440 to trigger acalculation of the thresholds.

To determine whether the calibrator 320 of FIG. 4 should be in thelearning mode or the recalibration mode, the example time logger 422checks the example threshold storage device 394 of FIG. 3 to determineif thresholds have already been generated. When thresholds are notdetected in the example threshold storage device 394 of FIG. 3, theexample time logger 422 of FIG. 4 operates in the learning mode. Whenthresholds are detected in the example threshold storage device 394 ofFIG. 3, the example time logger 422 of FIG. 4 operates in therecalibration mode.

The learning mode of the example calibrator 320 of FIG. 4 enables simpleand efficient installations of the meter 120 into a monitored site 98.As described above, when the example calibrator 320 is in learning mode,the calibration period is a relatively short period of time, such asfive minutes. As a result, a field representative installing the meter120 can utilize the learning mode to quickly determine whether theexample meter 120 of FIG. 1 is operating properly. In the illustratedexample, the meter 120 is calibrated by placing the informationpresentation device 102 in an OFF state and measuring the power drawn bythe information presentation device 102 via the sensor 110. The measuredamount of power drawn when the information presentation device 102 is inthe OFF state is used as an OFF threshold for the learning mode. Thus,the learning mode of the calibrator 320 results in an OFF thresholdbased on the standard OFF state of the information presentation device102. In the illustrated example, the ON threshold is calculated as amultiple of the OFF threshold because the information presentationdevice 102 was not placed in an ON state during the calibration period.However, it is also possible to calculate an OFF threshold and an ONthreshold during the learning mode by switching the informationpresentation device 102 from an OFF state to an ON state, or vice versa.Additionally and/or alternatively, predetermined ON and OFF thresholdsbased on the monitored information presentation device 102 may be used.For example, during the learning mode, the calibrator 320 may calculatethe ON and OFF thresholds based on characteristics (e.g., display size,type (e.g., LED, plasma, etc.), model, brand, etc.) of the informationpresentation device 102 identified by the user or field representative.In such instances, the identified characteristics can be used to lookup(e.g., in a database or chart) corresponding ON/OFF thresholdinformation. In some examples, the calibrator 320 retrieves thepredetermined ON and OFF thresholds from the example central facility160 of FIG. 1. In some examples, the calibrator 320 stores predeterminedON and OFF thresholds in a local memory or register.

The recalibration mode allows automatic updates of the thresholds usedto determine the state of the information presentation device 102 afterthe learning mode over a longer period of time, such as everytwenty-four hours. The example information presentation device 102enables users to change one or more power settings such that theinformation presentation device 102 powers down and/or up usingdifferent amounts of power than during standard ON/OFF conditions. Whena user changes such setting(s) of the information presentation device102, the power drawn by the information presentation device 102 whileOFF also changes. For example, enabling a Fast Start mode of theinformation presentation device 102 causes the information presentationdevice 102 to remain in a standby state when instructed to power down(e.g., via an OFF button of an input device (e.g., remote control)associated with the information presentation device 102) such that notall components of the information presentation device 102 are fullypowered down. Such a mode enables a faster startup time for theinformation presentation device 102 because some components are alreadyat least partially powered when the user instructs the informationpresentation device 102 to power up (e.g., via a remote control).Utilizing additional or alternative types of modes can change the amountof power drawn by the information presentation device 102 while in anOFF state or an ON state.

If the user enables a mode that changes the amount of power drawn whenthe information presentation device 102 is not presenting media to theuser after the initial learning mode of the meter 120 is performed, thethresholds generated by the calibrator 320 during the learning mode maylead to inaccurate state determinations by the state detector 370. Thatis, because certain user-enabled modes of the information presentationdevice 102 can increase or decrease the power draw of an informationpresentation device 102 in the OFF state, state determinations based onthresholds generated during the learning mode would be incorrect. Theexample calibrator 320 of FIG. 4 addresses this problem using therecalibration mode, which automatically adapts to such operating modechanges (e.g., activation of a Fast Start mode) by generating newthresholds representative of the currently enabled power mode(s) of theinformation presentation device. By automatically recalibrating (e.g.,updating) the generated thresholds at defined intervals (e.g., everytwenty-four hours) and/or by being responsive to enablement/disablementof operating modes by a user, the thresholds used by the example statedetector 370 of FIG. 3 reflect up-to-date power settings and/or modes ofthe information presentation device 102 and, thus, facilitate accuratestate detection of the information presentation device 102.

To generate the updated thresholds, the example power logger 424repeatedly (e.g., continuously, aperiodically or periodically (e.g.,every second)) receives power measurements from the example sensor 110of the example power supply 111 of FIG. 2. As a result, powermeasurements, including power measurements sensed during statetransitions, are received. To address power measurements notrepresentative of defined power states (e.g., power measurements sensedduring state transitions, during fluctuations in the commercial powersupply (e.g., power surges at the power source 101 of FIG. 1 during astorm), etc.), the example power logger 424 creates a log of stablepower measurements based on a comparison of received power measurementsand a running average of received power measurements. In some examples,a thirty second running average of power measurements is compared withthe received power measurements before logging a power measurement.However, alternate averages over other periods of time are possible. Thecomparisons (which are described in detail below) of the received powermeasurements to the running average before logging the measurementsenable the logged power measurements to represent stable power levels(e.g., power levels representative of different identifiable powerstates). Additionally, the comparisons to the running average utilizedby the example power logger 424 prevent fluctuations in the commercialpower supply (e.g., power surges at the power source 101 of FIG. 1during a storm) sensed by the example sensor 110 of FIG. 2 from skewingthe logged power measurements used by the example thresholds generator440 when generating thresholds.

The example running average calculator 426 of the example power logger424 of FIG. 4 calculates a running average of power measurementsreceived from the example sensor 110 of FIG. 2. In the illustratedexample of FIG. 4, the running average calculator 426 receives a powermeasurement every second and calculates a running average over a periodof time and/or number of readings such as, for example, thirty secondsand/or thirty readings. Thus, the example running average calculator 426of FIG. 4 averages the previous thirty power measurements to generatethe current value of the running average.

In the illustrated example, the power logger 424 of FIG. 4 includes acomparator 428, which compares the running average of received powermeasurements with a newly received power measurement before triggeringthe logging value recorder 430 to log a power measurement. When thereceived power measurement differs from the current value of the runningaverage by a threshold amount (e.g., a minimum percentage such as twentypercent), the example power logger 424 of FIG. 4 discards the powermeasurement received from the sensor 110. When the received powermeasurement is discarded, the example logging value recorder 430 of FIG.4 logs the previously logged power measurement (e.g., the last powermeasurement that did not differ from the corresponding value of therunning average by the threshold amount). In other words, in lieu oflogging the current measurement, the example logging value recorder 430re-logs the most recent previous power measurement. On the other hand,when the received power measurement is within the threshold amount(e.g., plus or minus twenty percent) of the current value of the runningaverage, the example logging value recorder 430 logs the newly receivedpower measurement. As a result, the values logged by the example loggingvalue recorder 430 of FIG. 4 represent stable power measurements. Whenstable power measurements are logged, fluctuations in power (e.g., apower surge) that are not representative of state changes by themonitored information presentation device 102 are eliminated and, thus,not logged as power states. Instead, sensed power levels of similarvalues (e.g., within the threshold) are grouped into separatelyidentified states. Because stable power measurements are logged and usedas a basis to generate the ON and OFF thresholds, accurate ON and OFFstate power measurements are identified by the example thresholdsgenerator 440 of FIG. 4.

FIG. 5A is an example list 500 representative of values generated by theexample power logger 424 of FIG. 4. The example list 500 of FIG. 5Aincludes power measurements 502 received from the sensor 110 of FIGS. 1and/or 2 and a running average value 504 calculated by the examplerunning average calculator 426 of FIG. 4. To generate the examplerunning average 504 of FIG. 5A, the example running average calculator426 uses a five second period (e.g., the previous five powermeasurements that are received every second) when calculating theaverage and rounds each calculated value to the nearest whole number.Alternative periods of time may be used.

Referring to a first example point 508 in the list 500, in this example,it is assumed the example power logger 424 of FIG. 4 receives a powermeasurement of twenty (e.g., Watts) from the example sensor 110 of FIG.2. Further, the example running average calculator 426 of FIG. 4calculates an average value for the previous five seconds. At the firstexample point 508 in the example list 500, the example running averagecalculator 426 of FIG. 4 sums the power measurements for the previousfive second period (e.g., 20+15+8+3+3=49) and divides the resulting sumby the number of summed measurements, which in this case is five. At thefirst example point 508 in the list 500 of FIG. 5A, the resulting valueof the running average is 9.8 (e.g., 49/5), which is rounded to thenearest whole number, which is ten.

The example comparator 428 of FIG. 4 compares the power measurement 502received from the sensor 110 of FIG. 2 and the corresponding runningaverage value 504 generated by the example running average calculator426 (e.g., by computing the difference between the running average value504 and the power measurement 502). The example comparator 428 of FIG. 4then compares the difference between the power measurement 502 and thecorresponding running average value 504 to the threshold amount. In theillustrated example of FIG. 5A, the threshold is twenty percent. Inother words, the example comparator 428 of FIG. 4 determines whether thepower measurement 502 is greater than or less than the correspondingrunning average value 504 by twenty percent. For instance, at the firstexample point 508 in the list 500, the example comparator 428 compares apower measurement value of twenty (20) and a corresponding runningaverage value of ten (10). In this example, twenty percent of therunning average value is two (2) and, thus, the acceptable power range(e.g., within the threshold amount) is from eight (8) to twelve (12)(e.g., plus or minus twenty percent of the running average value). Atthe first example point 508 of the list 500, the example comparator 428determines that the power measurement (e.g., twenty) does not fallwithin the acceptable difference range (e.g., eight to twelve) and,thus, outputs an appropriate negative indication (e.g., no, 0, false,null, etc.) to the example logging value recorder 430 of the examplepower logger 424 of FIG. 4. When the example comparator 428 of theexample power logger 424 of FIG. 4 determines that the power measurementfalls within the acceptable difference range, the example comparator 428outputs a positive indication (e.g., yes, 1, true, etc.) to the examplelogging value recorder 430. Although the above example mentions onecomparator 428, the example comparator 428 performs two comparisons and,thus, may include two or more comparators. For example, a firstcomparator may compare the received power measurement to the lesservalue of the acceptable range (e.g., eight) and a second comparator maycompare the received power measurement to the greater value of theacceptable range (e.g., twelve).

The example logging value recorder 430 of the example power logger 424of FIG. 4 receives the power measurement from the example sensor 110 ofFIGS. 1 and/or 2 and the indication output from the example comparator428. When the example logging value recorder 430 of FIG. 4 receives apositive indication (e.g., representation that the power measurement iswithin the acceptable difference range) in connection with a powermeasurement value from the comparator 428, the example logging valuerecorder 430 of FIG. 4 logs the value of the received power measurement(e.g., in the logged value portion 506 of the example list 500 of FIG.5A). When the example logging value recorder 430 receives a negativeindication (e.g., power measurement is not within the acceptabledifference range) in connection with a power measurement value from thecomparator 428, the example logging value recorder 430 logs thepreviously logged power measurement. As shown in the example list 500 ofFIG. 5A, a previous power measurement value (three) is logged at thefirst example point 508. Because the value of twenty (20) is outside theacceptable range of eight (8) to twelve (12) for the first point 508 inthe list 500, the example logging value recorder 430 receives the powermeasurement of twenty (20) and a negative indication from the examplecomparator 428. As a result, the example logging value recorder 430discards the received power measurement and logs the previous powermeasurement (e.g., three) in the logged value portion 506 of the list500. Rather than logging the transition power measurements receivedduring the transition (e.g., twenty), the logged power measurement(e.g., three) represents a stable power measurement. As shown in theexample list 500 of FIG. 5A, a current power measurement value (thirty)is logged at the second example point 509. Because the value of thirty(30) is within the acceptable range of twenty-one (21) to thirty-one(31) for the second point 509 in the list 500 (e.g., plus or minustwenty percent of the running average value (26), the example loggingvalue recorder 430 receives the power measurement of thirty (30) and apositive indication from the example comparator 428. As a result, theexample logging value recorder 430 logs the current power measurementvalue (e.g., 30) in the logged value portion 506 of the list 500.

An example benefit of logging values based on received powermeasurements and running averages includes preventing power measurementsvery close to each other (e.g., 41, 42, 43) from each being logged asindependent power states. Another example benefit includes eliminatinglogging (and, thus, basing the thresholds on) power measurements due tofluctuations (e.g., power surges, etc.) in the power drawn by theexample information presentation device 102.

The example power logger 424 can utilize additional and/or alternativetechniques to generate a list of logged values. FIG. 5B is an examplelist 550 generated in accordance with an example alternative to thetechnique described above in connection with FIG. 5A.

Similar to the example list 500 of FIG. 5A, the example list 550 of FIG.5B includes power measurements 510, running average values 512calculated by the example running average calculator 426 and loggedvalues 552. The running average value 512 of the example list 550 ofFIG. 5B is calculated similar to the running average value 504 of theexample list 500 of FIG. 5A and uses a five second period time. As thevalues of the power measurements 510 of FIG. 5B are the same as thepower measurements 502 of FIG. 5A and the running average is calculatedin FIG. 5B in the same manner as in FIG. 5A, the power measurementvalues (502, 510) and the running average values (504, 512) are the sameacross FIGS. 5A and 5B.

To generate the example list 550 of FIG. 5B, the logging value recorder430 maintains a flag 560 that establishes a requisite number ofindications of a power transitions before the logged value 552 can bechanged from a previous value. As described below, when a requisitenumber of transition indications (e.g., running average values differingfrom previously logged values by at least a threshold amount haveoccurred, the flag is set to enable a new value to be logged rather thanlogging the same value from a previous iteration. By utilizing a flag todetermine whether to log a new value (e.g., the current running averagevalue 512) or the previously logged value 552, the example power logger424 minimizes logging values due to short-term deviations in runningaverage values 512. For example, large changes (e.g., greater than thethreshold amount) in the running average values 512 due to fluctuationsin the commercial power supply (e.g., power surges at the example powersource 101 during a storm) or while transitioning between power states(e.g., transitioning from the OFF power state to the ON power state) arenot logged by the example power logger 424. As a result, the examplepower logger 424 creates a log of stable values representative of powermeasurements sensed by the example sensor 110 of FIGS. 1 and/or 2.Although the following describes a one (1) count requisite number ofconsecutive number of positive indications to set the flag 560 (e.g.,set to one), any number of consecutive number of positive indicationsmay be used to set the flag 560. For example, a five (5) count mayrequire the example logging value recorder 430 to receive five (5)consecutive positive indications from the example comparator 428 to setthe flat 560 (e.g., set to one).

While the example list 500 of FIG. 5A is generated via comparing thepower measurement values 502 to the corresponding running average values504, the example power logger 424 of FIG. 4 utilizes comparison(s) ofrunning average values 512 to previously logged values 552 to generatethe list 550 of FIG. 5B. As described in detail below, for a currentlyreceived power measurement, the corresponding running average value iscomputed and compared to the prior entry in the logged value portion 552of the list 550. In particular, the example comparator 428 of FIG. 4compares the running average value 512 and the previously logged value552 by computing their difference. The example comparator 428 of FIG. 4compares the computed difference to a threshold amount. In theillustrated example of FIG. 5B, the example threshold amount is plus orminus twenty percent. In other words, the example comparator 428 of FIG.4 determines whether the running average value 512 is greater than (orequal to) or less than (or equal to) the previously logged value 552 bytwenty percent.

Referring to a first example point 556 in the list 550, the examplerunning average calculator 426 calculates a running average value offour (4). The example comparator 428 compares the running average value512 at the first example point 556 (e.g., four) to the previously loggedvalue 552 (e.g., three), which corresponds to a second example point 558in the list 550 occurring immediately prior to the first point 556. Atthe first example point 556 of the list 550, the example comparator 428determines the running average value (four) falls outside the thresholdamount of difference (e.g., plus or minus twenty percent) from thepreviously logged value (three). As a result, the comparator 428 outputsa positive indication (e.g., yes, 1, true, etc.) to the example loggingvalue recorder 430. On the other hand, when the example comparator 428of the example power logger 424 of FIG. 4 determines the running averagevalue 512 falls within the threshold amount (e.g., differs from thepreviously logged value 552 by less than twenty percent), the examplecomparator 428 outputs a negative indication (e.g., no, 0, false, null,etc.) to the example logging value recorder 430 of the example powerlogger 424 of FIG. 4.

The example logging value recorder 430 of the example power logger 424of FIG. 4 receives the running average value 512 from the examplerunning average calculator 426 and the indication (e.g., positive ornegative) from the example comparator 428. The example logging valuerecorder 430 also maintains a flag 560. In the illustrated example ofFIG. 5B, the state of the flag 560 indicates whether the example loggingvalue recorder 430 is to log the previously logged value or the runningaverage value. When the flag 560 is set (e.g., set to one), the examplelogging value recorder 430 has received a requisite number ofconsecutive positive indications from the example comparator 428 andstores the running average value. Otherwise, the example logging valuerecorder 430 discards the received running average value and logs thepreviously logged value. In the illustrated example of FIG. 5B, therequisite number of positive indications to set the flag is one (1). Inother words, when the running average value is logged by the examplelogging value recorder 430, the difference between the running averagevalue and the previously logged value has been greater than thethreshold amount for two consecutive counts (e.g., one count to set theflag 560 and a second count to log the running average value). Forexample, when a monitored information presentation device 102 istransitioning from the OFF power state to the ON power state, asufficiently large deviation (e.g., greater than the threshold amount)in the running average values 512 results in consecutive positiveindications from the comparator 428. As a result, the example loggingvalue recorder 430 logs the running average value. In addition tologging the running average value 512, the example logging valuerecorder 430 resets the flag 560 (e.g., set to zero) and, in effect,resets the count of consecutive positive indications received from theexample comparator 428 to zero.

On the other hand, when the flag 560 is not set (e.g., the flag is setat zero), the example logging value recorder 430 has not received therequisite number of consecutive positive indications (e.g., one) to setthe flag 560 (e.g., to one). As a result, the example logging valuerecorder 430 logs the previously logged value instead of the runningaverage value. In the illustrated example, depending on the indicationreceived from the example comparator 428, the example logging valuerecorder 430 may set the status of the flag 560 (e.g., to one) or mayreset the status of the flag 560 (e.g., to zero) after logging thepreviously logged value.

By way of example, at the second example point 558 of FIG. 5B, thedifference between the running average value 512 (e.g., three) and thepreviously logged value 552 (e.g., three) is less than the thresholdamount (e.g., twenty percent) and the example comparator 428 outputs anegative indication. As a result, the example logging value recorder 430logs the previously logged value (e.g., three) instead of the runningaverage value at the second example point 558. Additionally, because ofthe received negative indication, the status of the flag 560 at thesecond example point 558 is reset (e.g., set to zero) by the examplelogging value recorder 430. At the next received power measurement 510from the example sensor 110 of FIGS. 1 and/or 2 (e.g., the first examplepoint 556), the example comparator 428 outputs a positive indication(e.g., the difference between the running average value 512 (e.g., four)and the previously logged value 552 (e.g., three) is greater than orequal to the threshold amount (e.g., twenty percent)). Because thestatus of the flag 560 at the second example point 558 was reset (e.g.,set to zero), the example logging value recorder 430 logs the previouslylogged value (e.g., three) instead of the running average value at thefirst example point 556. In addition to logging the previously loggedvalue, the example logging value recorder 430 sets the status of theflag 560 (e.g., set to one) because the requisite number of consecutivepositive indications to set the flag 560 (e.g., one) was met. At thenext calculated running average value 512 (e.g., the third example point562), the example comparator 428 outputs a positive indication to theexample logging value recorder 430 (e.g., the difference between therunning average value 512 (e.g., six) and the previously logged value(e.g., three) is greater than or equal to the threshold amount (e.g.,twenty percent)). As the status of the flag 560 at the previous point(e.g., the first example point 556) was previously set (e.g., set toone), the example logging value recorder 430 logs the received runningaverage value (e.g., six) and resets the status of the flag 560 (e.g.,set to zero).

The example thresholds generator 440 of FIG. 4 uses the stable loggedpower measurements 506 of the list 500 of FIG. 5A generated by theexample power logger 424 to generate thresholds to be used by theexample state detector 370 of FIG. 3. As described in detail below, whenthe sensed power measurements from the example sensor 110 of FIG. 1 arecompared with the generated thresholds, the example state detector 370of FIG. 3 detects the state of the example information presentationdevice 102. To identify the thresholds (e.g., during the learning mode)and/or adjust the thresholds (e.g., during the recalibration mode), theexample thresholds generator 440 creates a power chart based on aplurality of power measurements 506 (FIG. 5A) logged by the examplepower logger 424 of FIG. 4. Using the generated power chart, the examplethresholds generator 440 identifies an OFF state power measurement(e.g., the power drawn by the monitored information presentation device102 while in the OFF state). Depending on the mode of the examplecalibrator 320 of FIG. 3 (e.g., learning mode, recalibration mode), theexample thresholds generator 440 of FIG. 4 calculates the ON state powermeasurement differently. Based on the identified state powermeasurements (e.g., ON, OFF), the example thresholds generator 440 ofFIG. 4 calculates an ON and OFF threshold.

FIG. 6 is an example implementation of the example thresholds generator440 of FIG. 4. In the illustrated example of FIG. 6, the thresholdsgenerator 440 of FIG. 6 generates a power chart and thresholds (e.g., ONthreshold, OFF threshold) based on the power chart. The examplethresholds generator 440 of FIG. 6 includes a power chart generator 642,a chart analyzer 644 and a power level calculator 646. When thecalibration period has expired (e.g., learning mode calibration period,recalibration mode calibration period), the example power chartgenerator 642 of FIG. 6 retrieves logged values from the list 500generated by the example power logger 424 of FIG. 4 during thecalibration period.

The example power chart generator 642 includes a tallier 602 and asimilar value comparator 604. The example tallier 602 of FIG. 6 talliesthe number of entries logged at each unique power measurement andgenerates a power chart using the tallies. In other words, when the list500 of FIG. 5A includes a logged value 506 of three, the example tallier602 counts the number of occurrences of ‘three’ in the logged values 506of the list 500 during the calibration period (e.g., the previous daywhen in the recalibration mode) and updates the power chart at eachcount. When a retrieved logged value 506 is a new value (e.g., a valuenot in the power chart) and encountered by the example tallier 602, theexample tallier 602 checks with the example similar value comparator 604to determine whether the retrieved logged value 506 is similar to avalue already tallied in the power chart within a threshold. In theillustrated example of FIG. 6, the similar value comparator 604 uses agraduated scale to compare whether two numbers are similar enough to betreated as corresponding to the same power state. For example, theexample similar value comparator 604 uses a table such as, for example,the example comparison table 700 illustrated in FIG. 7A, to comparewhether two numbers are sufficiently similar. The degree of necessarysimilarity varies depending on the magnitude of the value at issue. Inthe illustrated table 700 of FIG. 7A, when a newly encountered loggedvalue 506 from the list 500 in the power chart is greater than 26 Watts,the example similar value comparator 604 determines whether the newlogged value 506 falls within a 10% range of any of the logged values inthe power chart. For example, if the power chart includes a logged value506 of thirty (e.g., Watts), the example similar value comparator 604determines whether the new logged value 506 is within 10% of ‘thirty’(e.g., 27-33). When the retrieved logged value 506 is sufficientlysimilar (e.g., within the comparison range of 10% of thirty) to anexisting value of the power chart, the tallier 602 increments the countfor the existing value. In other words, a retrieved logged value 506between 27 and 33 would lead to the count for ‘thirty’ being incrementedin the power chart. When the retrieved logged value 506 is not similarto a logged value 506 in the power chart (e.g., not within thecomparison range), the example tallier 602 adds the retrieved loggedvalue 506 to the power chart. Other example comparison ranges are shownin the example table 700 of FIG. 7A for different logged values. Forexample, when the logged value 506 in the power chart is between 1 Wattand 2 Watts, the example similar value comparator 604 uses a 200%comparison range to determine if a retrieved logged value 506 is similarto the logged value 506 in the power chart. When the logged value 506 inthe power chart is anywhere between 3 Watts and 6 Watts, the examplesimilar value comparator 604 uses a 50% comparison range to determine ifa retrieved logged value 506 is similar to the logged value 506 in thepower chart. The example similar value comparator 604 of FIG. 6 uses a30% comparison range when the logged value 506 in the power chart isanywhere between 7 Watts and 15 Watts. The example similar valuecomparator 604 of FIG. 6 uses a 20% comparison range when the loggedvalue 506 in the power chart is anywhere between 16 Watts and 25 Watts.

As each of the entries of the list 500 correspond to an amount of time(e.g., one second), the number of entries logged at a certain powermeasurement (e.g., three) corresponds to an amount of time for whichthat power measurement was logged. In some examples, the tallier 602also calculates the percent of time of the calibration period logged foreach power measurement.

FIG. 7B is an example power chart 750 representative of values generatedby the example power chart generator 642 of FIG. 6 during a separatetime period than the example list 500 of FIG. 5A was generated. Theexample power chart 750 of FIG. 7B identifies unique power measurementslogged in an example list (e.g., 3 Watts, 55 Watts, 23 Watts, and 14Watts) in a first column 752, the number of times each power measurement(e.g., including similarly logged values) was logged in a second column754 (e.g., because a log corresponds to one second, the number alsocorresponds to a number of seconds spent in the corresponding state),and the percentage of time spent at each logged power measurement in athird column 756. In the illustrated example power chart 750 of FIG. 7B,a three hundred second (e.g., five minute) calibration period was used.However, alternative periods of time can be used. In the illustratedexample, the example tallier 602 counted two hundred twenty-two entriesof 3 Watts, sixty-six entries of 55 Watts, nine entries of 23 Watts, andthree entries of 14 Watts logged by the example power logger 424 of FIG.4. The example power chart 750 of FIG. 7B shows that the percentage oftime tallied for the power measurement of 3 Watts during the calibrationperiod is seventy-four percent (e.g., 222/300*100=74%). Similarcalculations are performed to populate the other rows of the percentagecolumn 756.

The example chart generator 642 of FIG. 6 stores the generated powerchart 750 in the example chart storage device 392 of FIG. 3. Further,the power chart 750 is accessed for analysis by the example chartanalyzer 644 of FIG. 6. Alternatively and/or additionally, the examplechart generator 642 outputs the generated power chart 750 to the examplechart analyzer 644 of FIG. 6. The example chart analyzer 644 sorts thechart based on the amount of time tallied for each power measurement.For example, the chart analyzer 644 sorts the chart from greatest toleast amount of time. In the illustrated example, the logged entries inthe generated power chart 750 are organized (e.g., sorted) from mosttime to least time (of the time column 754) by the example chartanalyzer 644. The example chart analyzer 644 then identifies the twomost frequently logged power measurements in the power chart 750. Forexample, in the example power chart 750 of FIG. 7B, the example chartanalyzer 644 identifies 3 Watts and 55 Watts as the most frequentlylogged power measurements. Identifying a different number of frequentlylogged power measurements is also possible. For example, a chartanalyzer 644 can identify the four most frequently logged measurements.The example chart analyzer 644 identifies the most frequent powermeasurements based on an assumption that the information presentationdevice 102 is either in an ON state or an OFF state for a majority ofthe time, rather than in a transitional state, such as powering up orpower off.

In the illustrated example of FIG. 6, the example power level calculator646 utilizes the two most frequently logged power measurements from theexample chart analyzer 644. In particular, the example power levelcalculator 646 of FIG. 6 identifies the lesser value of the two receivedpower measurements as the OFF state power measurement. The identifiedOFF state power measurement represents the sensed power drawn by theinformation presentation device 102 while in the OFF state. In theillustrated example, when the power level calculator 646 of FIG. 6receives the power measurements identified by the chart analyzer 644(e.g., 3 Watts and 55 Watts), the power level calculator 646 identifiesthe 3 Watts power measurement as the OFF state power measurement.

As described above, the example time logger 422 of FIG. 4 maintainstiming information to control different calibration modes of the examplecalibrator 320 of FIG. 3. When the example calibrator 320 of FIG. 3 isin the recalibration mode, the example power level calculator 646 ofFIG. 6 identifies the greater of the two received power measurementsfrom the example chart analyzer 644 as the ON state power measurement.For example, when the example power level calculator 646 receives thepower measurements identified in the example power chart 750 of FIG. 7B(e.g., 3 Watts and 55 Watts) by the example chart analyzer 644, theexample power level calculator 646 identifies the 55 Watts powermeasurement as the ON state power measurement.

When the example calibrator 320 of FIG. 3 is in the learning mode, theexample power level calculator 646 of FIG. 6 determines the ON statepower measurement based on the OFF state power measurement. In order toidentify an accurate OFF state power measurement, in some examples, theinformation presentation device 102 is left in the OFF state for theduration of the learning period. As a result, the power chart is notused to identify an ON state power during the learning mode. Instead,the example power level calculator 646 of FIG. 6 calculates the ON statepower measurement as five times the OFF state power measurement when inthe learning mode. In some examples, the power level calculator 646 ofFIG. 6 compares the calculated ON state power measurement with athreshold expected ON value (e.g., a minimum value expected for an ONstate). For example, when the calculated ON state power measurement isless than the threshold expected ON value, the calculated state powermeasurement is discarded and the threshold expected ON value is set asthe ON state power measurement. By using this threshold, the examplethresholds generator 440 of FIG. 6 is able to adapt to the wide range ofpower settings included in modern information presentation devices 102.For example, some new energy star televisions draw less than 2 Wattswhile in the OFF state, but draw anywhere between 30 and 200 Watts inthe ON state. In such an example, calculating the ON state powermeasurement by multiplying the OFF state power measurement (e.g., 2Watts) yields an inaccurate ON threshold (e.g., 10 Watts) and theexample state detector 370 of FIG. 3 would, thus, yield inaccurate powerstates if such a threshold were employed. Therefore, the thresholdexpected ON value (e.g., 50 Watts) is used by the example thresholdsgenerator 440 to generate the ON threshold in such circumstances.

The example thresholds generator 440 of FIG. 6 includes an OFF thresholdcalculator 648, an ON threshold calculator 650 and a thresholds checker652. In the illustrated example of FIG. 6, the example OFF thresholdcalculator 648 receives the OFF state power measurement from the examplepower level calculator 646 based on the power chart 750. The example OFFthreshold calculator 648 calculates an OFF threshold that is greaterthan the OFF state power measurement. In some examples, the example OFFthreshold calculator 648 uses a graduated scale to calculate the OFFthreshold. For example, the example OFF threshold calculator 648 uses atable such as, for example, the example table 800 illustrated in FIG. 8,to calculate the OFF threshold. In the illustrated table 800 of FIG. 8,when the OFF state power measurement calculated by the power levelcalculator 646 is anywhere from 3 Watts to 10 Watts, the example OFFthreshold generator 648 calculates the OFF threshold by multiplying theOFF state power measurement by two. Other example multipliers are shownin the example table 800 of FIG. 8 for different power levels. Forexample, when the OFF state power measurement calculated by the powerlevel calculator 646 is anywhere from 10 Watts to 20 Watts, the exampleOFF threshold generator 648 calculates the OFF threshold by multiplyingthe OFF state power measurement by 1.5. When the OFF state powermeasurement calculated by the power level calculator 646 is greater than20 Watts, the example OFF threshold generator 648 calculates the OFFthreshold by multiplying the OFF state power measurement by 1.2, basedon the illustrated table 800 of FIG. 8. The example OFF thresholdgenerator 648 sets the OFF threshold at 5 Watts when the OFF state powermeasurement is 2 Watts, and sets the OFF threshold at 3 Watts when thenOFF state power measurement is 1 Watt.

In the illustrated example of FIG. 6, the example ON thresholdcalculator 650 receives the ON state power measurement from the examplepower level calculator 646 based on the power chart 750. The example ONthreshold calculator 650 calculates an ON threshold that is less thanthe ON state power measurement reflected in the power chart 750. In someexamples, the example ON threshold calculator 650 uses a graduated scaleto calculate the ON threshold. For example, the example ON thresholdcalculator 650 uses a table such as, for example, the example table 900illustrated in FIG. 9, to generate the ON threshold. In the illustratedtable 900 of FIG. 9, when the ON state power measurement is between 70Watts and 100 Watts, the example ON threshold generator 650 calculatesthe ON threshold by multiplying the ON state power measurement by 0.7.Other example multipliers are shown in the example table 900 of FIG. 9for different power levels. For example, when the ON state powermeasurement is less than 70 Watts, the example ON threshold generator650 calculates the ON threshold by multiplying the ON state powermeasurement by 0.6. When the ON state power measurement is greater than100 Watts, the example ON threshold generator 650 calculates the ONthreshold by multiplying the ON state power measurement by 0.8, based onthe illustrated table 900 of FIG. 9.

In the illustrated example of FIG. 6, the example thresholds checker 652compares the ON threshold generated by the example ON thresholdcalculator 650 to the OFF threshold generated by the example OFFthreshold calculator 648. In the illustrated example, the thresholdschecker 652 determines whether the ON threshold differs from the OFFthreshold by an ON/OFF difference threshold (e.g., twenty percent). Theexample thresholds checker 652 compares the ON threshold and OFFthreshold because certain scenarios can yield undesirable thresholds.For example, when the information presentation device 102 is left in theOFF state for the entire recalibration period (e.g., the informationpresentation device is unplugged from the power source 101), the examplethresholds generator 440 identifies the same power measurement as theOFF state power measurement and the ON state power measurement. In suchexamples, attempting to detect the state of the information presentationdevice 102 using these state power measurements would generateirrelevant and/or misleading data. Thus, the example thresholdsgenerator 440 of FIG. 6 checks whether the generated thresholds areacceptable. When the difference between the ON threshold and OFFthreshold is less than the ON/OFF difference threshold, the examplethresholds checker 652 outputs a negative indication (e.g., output a No,0, false). When the indication from the example thresholds checker 652of FIG. 6 is negative, the example threshold storage device 394 of FIG.3 discards the generated thresholds and re-stores the thresholdsgenerated during the previous calibration period.

When the difference between the ON threshold and OFF threshold isgreater than the ON/OFF difference threshold, the example thresholdschecker 652 of FIG. 6 outputs the ON and OFF threshold values and/or apositive indication that the received ON threshold and OFF thresholdpassed the check (e.g., output a Yes, 1, true). When the indication fromthe example thresholds checker 652 is positive, the example thresholdstorage device 394 of FIG. 3 stores the generated thresholds to be usedby the example state detector 370 of FIG. 3 during state detection ofthe information presentation device 102. Thus, the example calibrator320 of FIG. 3 continuously (e.g., repeatedly) calibrates the meter 120by identifying and/or adjusting the thresholds on which the statedeterminations of the example state detector 370 are based.

While an example manner of implementing the meter 120 of FIG. 1 has beenillustrated in FIG. 3, one or more of the elements, processes, and/ordevices illustrated in FIG. 3 may be combined, divided, re-arranged,omitted, and/or implemented in any other way. Further, the examplecalibrator 320, the example state detector 370, the example chartstorage device 392, the example threshold storage device 394, theexample state ID storage device 396 and/or, more generally, the examplemeter 120 of FIG. 3 may be implemented by hardware, software, firmwareand/or any combination of hardware, software and/or firmware. Thus, forexample, any of the example calibrator 320, the example state detector370, the example chart storage device 392, the example threshold storagedevice 394, the example state ID storage device 396 and/or, moregenerally, the example meter 120 of FIG. 3 could be implemented by oneor more circuit(s), programmable processor(s), application specificintegrated circuit(s) (ASIC(s)), programmable logic device(s) (PLD(s))and/or field programmable logic device(s) (FPLD(s)), etc. When any ofthe apparatus or system claims of this patent are read to cover a purelysoftware and/or firmware implementation, at least one of the examplecalibrator 320, the example state detector 370, the example chartstorage device 392, the example threshold storage device 394, and/or theexample state ID storage device 396 are hereby expressly defined toinclude a tangible computer readable medium such as a memory, DVD, CD,Blu-ray, etc. storing the software and/or firmware. Further still, theexample meter 120 of FIG. 3 may include one or more elements, processesand/or devices in addition to, or instead of, those illustrated in FIG.3, and/or may include more than one of any or all of the illustratedelements, processes and devices.

While an example manner of implementing the calibrator 320 of FIG. 3 hasbeen illustrated in FIG. 4, one or more of the elements, processes,and/or devices illustrated in FIG. 4 may be combined, divided,re-arranged, omitted, and/or implemented in any other way. Further, theexample time logger 422, the example power logger 424, the examplerunning average calculator 426, the example comparator 428, the examplelogging value recorder 430, the example thresholds generator 440 and/or,more generally, the example calibrator 320 of FIG. 4 may be implementedby hardware, software, firmware and/or any combination of hardware,software and/or firmware. Thus, for example, any of the example timelogger 422, the example power logger 424, the example running averagecalculator 426, the example comparator 428, the example logging valuerecorder 430, the example thresholds generator 440 and/or, moregenerally, the example calibrator 320 of FIG. 4 could be implemented byone or more circuit(s), programmable processor(s), application specificintegrated circuit(s) (ASIC(s)), programmable logic device(s) (PLD(s))and/or field programmable logic device(s) (FPLD(s)), etc. When any ofthe apparatus or system claims of this patent are read to cover a purelysoftware and/or firmware implementation, at least one of the exampletime logger 422, the example power logger 424, the example runningaverage calculator 426, the example comparator 428, the example loggingvalue recorder 430, and/or the example thresholds generator 440 arehereby expressly defined to include a tangible computer readable mediumsuch as a memory, DVD, CD, Blu-ray, etc. storing the software and/orfirmware. Further still, the example calibrator 320 of FIG. 4 mayinclude one or more elements, processes and/or devices in addition to,or instead of, those illustrated in FIG. 4, and/or may include more thanone of any or all of the illustrated elements, processes and devices.

While an example manner of implementing the thresholds generator 440 ofFIG. 4 has been illustrated in FIG. 6, one or more of the elements,processes, and/or devices illustrated in FIG. 6 may be combined,divided, re-arranged, omitted, and/or implemented in any other way.Further, the example power chart generator 642, the example chartanalyzer 644, the example power level calculator 646, the example OFFthreshold calculator 648, the example ON threshold calculator 650, theexample thresholds checker 652 and/or, more generally, the examplethresholds generator 440 of FIG. 6 may be implemented by hardware,software, firmware and/or any combination of hardware, software and/orfirmware. Thus, for example, any of the example power chart generator642, the example chart analyzer 644, the example power level calculator646, the example OFF threshold calculator 648, the example ON thresholdcalculator 650, the example thresholds checker 652 and/or, moregenerally, the example thresholds generator 440 of FIG. 6 could beimplemented by one or more circuit(s), programmable processor(s),application specific integrated circuit(s) (ASIC(s)), programmable logicdevice(s) (PLD(s)) and/or field programmable logic device(s) (FPLD(s)),etc. When any of the apparatus or system claims of this patent are readto cover a purely software and/or firmware implementation, at least oneof the example power chart generator 642, the example chart analyzer644, the example power level calculator 646, the example OFF thresholdcalculator 648, the example ON threshold calculator 650 and/or theexample thresholds checker 652 are hereby expressly defined to include atangible computer readable medium such as a memory, DVD, CD, Blu-ray,etc. storing the software and/or firmware. Further still, the examplethresholds generator 440 of FIG. 6 may include one or more elements,processes and/or devices in addition to, or instead of, thoseillustrated in FIG. 6, and/or may include more than one of any or all ofthe illustrated elements, processes and devices.

FIG. 10 is an example implementation of the example state detector 370of FIG. 3. In the illustrated example of FIG. 10, the state detector 370of FIG. 3 detects the state of an information presentation device suchas, for example, the information presentation device 102 of FIG. 1. Asdescribed above, the example state detector 370 of FIG. 3 determines thestate of the information presentation device 102 (e.g., ON or OFF) basedon a plurality of thresholds generated by the example calibrator 320 ofthe example meter 120 of FIG. 1. The example state detector 370 comparesthe received power measurements from the example sensor 110 of FIG. 2 tothe stored thresholds generated by the example calibrator 320 toidentify the state of the information presentation device 102. As theexample state detector 370 determines the state of the informationpresentation device 102, the example state detector 370 records thestate determinations in a state ID storage device 396 and/or transmitsthe state determinations (e.g., periodically, aperiodically,continuously) to the example central facility 160 of FIG. 1.

FIG. 11 is an example graph 1100 representative of power measurements1110 received by the example meter 120 of FIG. 3 via the sensor 110 overa period of time. The example graph 1100 includes an OFF threshold 1154and an ON threshold 1156 that correspond to values stored in the examplethresholds storage device 394 of FIG. 3. The example graph 1100 of FIG.11 is described in connection with the example state detector 370 ofFIG. 10 for purposes of illustration.

The example state detector 370 of FIG. 10 includes an OFF comparator1072, an ON comparator 1074, a previous state checker 1076, a timer1078, a back creditor 1080 and a creditor 1082. The example OFFcomparator 1072 of FIG. 10 compares a power measurement taken by theexample sensor 110 of FIGS. 1 and/or 2 and the OFF threshold from theexample threshold storage device 394. In the illustrated example, whenthe received power measurement 1110 is less than the OFF threshold 1154(e.g., as in the time period between T2 and T3), the example informationpresentation device 102 is determined to be in the OFF state by thestate detector 370. As a result, the example OFF comparator 1072 of FIG.10 outputs a positive indication (e.g., yes, 1, true, etc.) to thecreditor 1082 to indicate that the information presentation device 102is OFF (e.g., not outputting media). Conversely, when the received powermeasurement 1110 is greater than the OFF threshold, the informationpresentation device 102 could be in the ON state or an indeterminatestate (e.g., booting down). As a result, when the received powermeasurement 1110 is greater than the OFF threshold, the power state ofthe example information presentation device 102 is not known (to the OFFcomparator 1072) and the example OFF comparator 1072 of FIG. 10 outputsa negative indication (e.g., no, 0, false, etc.) to the example creditor1082.

In the illustrated example of FIG. 10, the ON comparator 1074 compares apower measurement from the example sensor 110 of FIGS. 1 and/or 2 andthe ON thresholds from the example threshold storage device 394. Withreference to the example graph 1100 of FIG. 11, when the received powermeasurement 1110 is greater than the ON threshold 1154 (e.g., during thetime period between T3 and T4), the example information presentationdevice 102 is determined to be in the ON state. As a result, the exampleON comparator 1074 of FIG. 10 outputs a positive indication to thecreditor 1082 that the information presentation device 102 is in an ONstate. In the illustrated example of FIG. 10, when the received powermeasurement is less than the ON threshold, the information presentationdevice 102 could be in the OFF state or the indeterminate state (e.g.,booting down). As a result, when the received power measurement is lessthan the ON threshold, the power state of the example informationpresentation device 102 is not known (to the ON comparator 1074) and theexample ON comparator 1074 of FIG. 10 outputs a negative indication tothe example creditor 1082.

As described above, when the received power measurement is between theOFF and ON thresholds (e.g., during the time period between T7 and T9 inthe example graph of FIG. 11), the power state of the informationpresentation device 102 is indeterminate. For example, the exampleinformation presentation device 102 may be, for example, turning OFF orthe example information presentation device 102 may be, for example,switching to a low power consuming state (e.g., Input mode or Blackscreen) and still in an ON state. When the received power measurement isdetermined to correspond to the information presentation device 102being in the indeterminate state (e.g., when the OFF comparator 1072 andthe ON comparator 1074 output a negative indication), the power state ofthe information presentation device 102 is determined based on theactions (e.g., transition up, transition down, etc.) of the informationpresentation device 102 while in the indeterminate state and from whichstate the information presentation device 102 transitioned into theindeterminate state.

In the illustrated example of FIG. 10, the example previous statechecker 1076 receives an indication from the example OFF comparator1072, an indication from the example ON comparator 1074 and the previousstate of the example information presentation device 102. In someexamples, the example previous state checker 1076 receives the previousstate from the example creditor 1082. In some examples, the exampleprevious state checker 1076 receives the previous state from the examplestate ID storage device 396 of FIG. 3. In other examples, the previousstate checker 1076 retains the previous state in a local memory orregister. When the example previous state checker 1076 of FIG. 10receives a negative indication (e.g., no, 0, false, etc.) from both theexample OFF comparator 1072 and the example ON comparator 1074, theexample previous state checker 1076 checks the received previous stateof the information presentation device 102 to determine whether theinformation presentation device 102 was previously in the OFF state orin the ON state. When the previous state of the example informationpresentation device 102 is the OFF state (e.g., during the indeterminatestate between T1 and T2 on the example graph of FIG. 11), the exampleprevious state checker 1076 of FIG. 10 outputs an indication that thepower state of the information presentation device 102 is in the ONstate because the OFF state power measurement is considered to be thelowest, stable power drawn by the example information presentationdevice 102 of FIG. 1. This assumption is valid because the informationpresentation device 102 does not draw less power while in any statecompared to the OFF state. As a result, in examples when the previouspower state is determined by the example previous state checker 1076 tobe in the OFF state, the example previous state checker 1076 of FIG. 10correctly determines the power state of the information presentationdevice 102 to be in the ON state.

When the example previous state checker 1076 of FIG. 10 determines theprevious power state of the example information presentation device 102was in the ON state, in some examples, the example previous statechecker 1076 outputs an indication that the information presentationdevice 102 power state is indeterminate. For example, the exampleinformation presentation device 102 may include a slow boot-down periodwhen transitioning from the ON state to the OFF state causing the powerdrawn by the information presentation device 102 to remain greater thanwhile in the OFF state (e.g., cooling fans continue to draw power untilthey turn off). In some examples, the example information presentationdevice 102 switches from an ON state to an energy efficient state (e.g.,an Input screen), thereby causing the power measurement to transitionfrom the ON state into the indeterminate state. Determining whether theexample information presentation device 102 of FIG. 1, is in a boot downor an energy efficient state helps accurately determine the power stateof the information presentation device 102. In some examples, an exampleinformation presentation device 102 may have a significant boot downperiod (e.g., between 30 seconds and 2 minutes) before the sensed powermeasurement by the example sensor 110 of FIG. 2 drops below the OFFthreshold. In some such examples, if the boot down period is incorrectlystored as in the ON state, inaccurate data regarding media exposure isgenerated for the example monitored site 98 of FIG. 1. For example, anadvertisement lasting only 30 seconds could be credited even though noexposure to the advertisement occurred. Thus, it is important toaccurately determine the power state of the example informationpresentation device 102 while the received power measurement is in theindeterminate state.

In the illustrated example of FIG. 10, the example timer 1078 initiatesa delay period when the example previous state checker 1076 outputs anindeterminate state (e.g., between OFF threshold 1154 and ON threshold1156 in the illustrated graph of FIG. 11). For example, the exampletimer 1078 begins a three minute countdown when initiated. However,alternative periods of time are possible. When the delay period isinitiated, in some examples, the example creditor 1082 of FIG. 10 delaysoutputting power states (e.g., to the example state ID storage device396 and/or the example central facility 160 of FIG. 1). As describedabove, some information presentation device's 102 include a boot downperiod when transitioning from the ON state to the OFF state and theboot down period may be for a significant period of time (e.g., between30 seconds and 2 minutes). Thus, a delay period longer than the bootdown period is selected. In some examples, a three minute delay periodsufficiently exceeds the boot down period observed in the exampleinformation presentation device 102.

In the illustrated example of FIG. 10, the example back creditor 1080receives information from the example timer 1078 indicating the statusof the delay period. The example back creditor 1080 of FIG. 10 monitorsthe power measurement sensed by the example sensor 110 of FIG. 2 duringthe delay period. When the power measurement during the delay perioddrops below the OFF threshold (e.g., is in the OFF state), the exampleback creditor 1080 of FIG. 10 determines the example informationpresentation device 102 was in a boot down period. In the illustratedexample graph of FIG. 11, the period between time T4 and time T5 is backcredited as OFF because the example power measurement 1110 drops belowthe example OFF threshold 1154 before the delay period (e.g., time T4 totime T6) expired. When the example back creditor 1080 identifies theboot down period, the example back creditor 1080 outputs data indicatingthe duration of the delay period spent in the indeterminate state shouldbe back credited as the information presentation device 102 in the OFFstate. For example, the example back creditor 1080 outputs data to theexample creditor 1082 of FIG. 10 to resume outputting power states ofthe example information presentation device 102. Additionally and/oralternatively, the example back creditor 1082 outputs data indicatingthe duration of the delay period in the indeterminate state should becredited as OFF. Thus, the example state detector 370 of FIG. 3correctly identifies the example information presentation device 102 wasno longer in the ON state and this information can be used (e.g., byaudience measurement entities) to accurately generate statisticsregarding media exposure at the example monitored site 98.

In some examples when the received power measurement does not drop below(e.g., is less than) the OFF threshold (e.g., remains in theindeterminate state and/or returns above the ON threshold) during theduration of the delay period (e.g., during the 3 minute delay period),the example back creditor 1080 of FIG. 10 correctly identifies theexample information presentation device 102 was not turned OFF. Rather,the example information presentation device 102 may have, for example,switched to an energy saving mode when media is still presented. Forexample, in the illustrated example graph of FIG. 11, the example powermeasurement 1110 remains in the indeterminate state during the entiredelay period (e.g., during the time period between time T7 and time T8).Thus, the duration of the delay period is properly credited as theinformation presentation device 102 in the ON state. Additionally, theexample back creditor 1080 of FIG. 10 outputs data indicating thatadditional power measurements in the indeterminate state should continueto be credited as in the ON state until the received power measurementdrops below the OFF threshold. For example, if a delay period of threeminutes is used and the sensed power measurement by the example sensor110 of FIG. 2 indicates the example information presentation device 102is in the indeterminate state for ten minutes before dropping below theOFF threshold (e.g., less than the OFF threshold), the three minutes ofthe delay period are back credited as ON once the delay period expiresand, going forward, the remaining seven minutes are also credited as inthe ON state. Thus, the example state detector 370 of FIG. 3 correctlyidentifies the example information presentation device 102 was in the ONstate and this information can be used (e.g., by audience measuremententities) to accurately generate statistics regarding media exposure atthe example monitored site 98.

In the illustrated example of FIG. 10, the creditor 1082 outputsdetected states of the example information presentation device 102. Insome examples, the creditor 1082 receives state information from the OFFcomparator 1072, the ON comparator 1074, the previous state checker1076, the timer 1078 and/or the example back creditor 1080. In someexamples, the example creditor 1082 embeds (e.g., appends, prepends,etc.) a time stamp to the output state. As a result, the example meter120 of FIG. 3 determines, for example, whether the example informationpresentation device 102 is in the ON state or the OFF state at a giventime and/or for a given period of time. In some examples, the examplecreditor 1082 of FIG. 10 delays (e.g., postpones) outputting powerstates, for example, when the example timer 1078 initiates a delayperiod. In some examples, the example creditor 1082 outputs datareceived from the example back creditor 1080 indicating the power stateof the example information presentation device 102 for at least aportion of the delay period. Thus, the example meter 120 of FIG. 3correctly detects the state of the example information presentationdevice 102 through repeatedly recalibrated thresholds and comparing thereceived (e.g., sensed) power measurements to the thresholds.

During operation of the example meter 120 of FIG. 3, unique power drawsituations may arise. For example, a user may leave the exampleinformation presentation device 102 in a state for the entirerecalibration period (e.g., left in the OFF state for the entirerecalibration period). In such instances, the example thresholdsgenerator 440 of FIG. 4 prevents thresholds from being set that yielduseless usage information by performing checks on the thresholds anddiscarding the useless thresholds.

In some examples, an example information presentation device 102 may beswitched into a new mode such as, for example, a Fast ON mode. In somesuch examples, the example information presentation device 102 does notcompletely turn OFF while in the OFF state. Rather, the exampleinformation presentation device 102 is set so that the exampleinformation presentation device 102 can be quickly turned back on (e.g.,light sources such as light bulbs and/or LEDs used to illuminate thescreen are not fully turned OFF and the startup time is greatlyreduced). In some such examples, the received (e.g., sensed) powermeasurement of the example information presentation device 102 does notgo below the calibrated OFF threshold when in the OFF state. However, asthe example calibrator 320 of FIG. 3 automatically recalibrates (e.g.,periodically, aperiodically, on a set schedule, when an event occurs,etc.), the detected states are not incorrect for an extended period oftime. Rather, the example calibrator 320 of FIG. 3 recalibrates a newOFF state power measurement and a new OFF threshold to reflect theupdated power mode of the example information presentation device 102.

While an example manner of implementing the state detector 370 of FIG. 3has been illustrated in FIG. 10, one or more of the elements, processes,and/or devices illustrated in FIG. 10 may be combined, divided,re-arranged, omitted, and/or implemented in any other way. Further, theexample OFF comparator 1072, the example ON comparator 1074, the exampleprevious state checker 1076, the example timer 1078, the example backcreditor 1080, the example creditor 1082 and/or, more generally, theexample state detector 370 of FIG. 10 may be implemented by hardware,software, firmware and/or any combination of hardware, software and/orfirmware. Thus, for example, any of the example OFF comparator 1072, theexample ON comparator 1074, the example previous state checker 1076, theexample timer 1078, the example back creditor 1080, the example creditor1082 and/or, more generally, the example state detector 370 of FIG. 10could be implemented by one or more circuit(s), programmableprocessor(s), application specific integrated circuit(s) (ASIC(s)),programmable logic device(s) (PLD(s)) and/or field programmable logicdevice(s) (FPLD(s)), etc. When any of the apparatus or system claims ofthis patent are read to cover a purely software and/or firmwareimplementation, at least one of the example OFF comparator 1072, theexample ON comparator 1074, the example previous state checker 1076, theexample timer 1078, the example back creditor 1080 and/or the examplecreditor 1082 are hereby expressly defined to include a tangiblecomputer readable medium such as a memory, DVD, CD, Blu-Ray, etc.storing the software and/or firmware. Further still, the example statedetector 370 of FIG. 10 may include one or more elements, processesand/or devices in addition to, or instead of, those illustrated in FIG.10, and/or may include more than one of any or all of the illustratedelements, processes and devices.

Flowcharts representative of example machine readable instructions forimplementing the meter 120 of FIGS. 1 and/or 3 and/or 14 are shown inFIGS. 12, 13 and 15. In the illustrated examples, the machine readableinstructions comprise a program for execution by a processor such as theprocessor 1612 shown in the example processing platform 1600 discussedbelow in connection with FIG. 16. The program may be embodied insoftware stored on a tangible computer readable medium such as a CD-ROM,a floppy disk, a hard drive, a digital versatile disk (DVD), a Blu-raydisk, or a memory associated with the processor 1612, but the entireprogram and/or parts thereof could alternatively be executed by a deviceother than the processor 1612 and/or embodied in firmware or dedicatedhardware. Further, although the example program is described withreference to the flowcharts illustrated in FIGS. 12, 13 and 15, manyother methods of implementing the example meter 120 may alternatively beused. For example, the order of execution of the blocks may be changed,and/or some of the blocks described may be changed, eliminated, orcombined.

As mentioned above, the example processes of FIGS. 12, 13 and 15 may beimplemented using coded instructions (e.g., computer readableinstructions) stored on a tangible computer readable storage medium suchas a hard disk drive, a flash memory, a read-only memory (ROM), acompact disk (CD), a digital versatile disk (DVD), a cache, arandom-access memory (RAM) and/or any other storage media in whichinformation is stored for any duration (e.g., for extended time periods,permanently, brief instances, for temporarily buffering, and/or forcaching of the information). As used herein, the term tangible computerreadable medium is expressly defined to include any type of computerreadable storage medium and to exclude propagating signals. Additionallyor alternatively, the example processes of FIGS. 12, 13 and 15 may beimplemented using coded instructions (e.g., computer readableinstructions) stored on a non-transitory computer readable medium suchas a hard disk drive, a flash memory, a read-only memory, a compactdisk, a digital versatile disk, a cache, a random-access memory and/orany other storage media in which information is stored for any duration(e.g., for extended time periods, permanently, brief instances, fortemporarily buffering, and/or for caching of the information). As usedherein, the term non-transitory computer readable medium is expresslydefined to include any type of computer readable storage medium and toexclude propagating signals. As used herein, when the phrase “at least”is used as the transition term in a preamble of a claim, it isopen-ended in the same manner as the term “comprising” is open ended.Thus, a claim using “at least” as the transition term in its preamblemay include elements in addition to those expressly recited in theclaim.

The example of FIG. 12 begins at an activation of the example meter 120(block 1200). The activation at the onset of the example of FIG. 3corresponds to, for example, the meter 120 being installed in ahousehold, such as the monitored site 98 of FIG. 1. The examplecalibrator 320 of FIG. 3 determines whether previously generatedthresholds are stored in the example threshold storage device 394 (block1205). If the example threshold storage device 394 does not includethreshold values, the example calibrator 320 operates in learning modeto generate thresholds and store the thresholds in the example thresholdstorage device 394 (block 1207). As described above, generation of thethresholds in the learning mode includes calibrating an OFF thresholdand setting an ON threshold in accordance with the example calibrator140 of FIGS. 3 and/or 4. An example implementation of block 1207 isdescribed below in connection with FIG. 13. When the thresholds havebeen generated in the learning mode, control proceeds to block 1210,which corresponds to a collection of power values from the examplesensor 110 for purposes of detecting a state of the informationpresentation device 102 (FIG. 1). Alternatively, if the thresholdstorage device 394 includes thresholds (block 1205), control proceeds toblock 1210.

To begin a determination of a current state of the informationpresentation device 102, the example state detector 370 of FIG. 3compares the current power value (e.g., measurement of power drawn bythe information presentation device 102) received from the examplesensor 110 of FIGS. 1 and/or 2 to an OFF threshold (e.g., an OFFthreshold calibrated during the learning mode and/or stored in theexample threshold storage device 394) (block 1215). If the power valuereceived from the example sensor 110 is less than the OFF threshold, theexample state detector 370 determines the example informationpresentation device 102 is in the OFF state (block 1217). Otherwise, ifthe power value received from the example sensor 110 is greater than orequal to the OFF threshold, the example state detector 370 proceeds tocompare the power value received from the example sensor 110 to an ONthreshold (e.g., an ON threshold set during the learning mode and/orstored at the example threshold storage device 394) (block 1220). If thepower value received from the example sensor 110 is greater than the ONthreshold, the example state detector 370 determines the exampleinformation presentation device 102 is in the ON state (block 1227).Otherwise, if the received power value is less than or equal to the ONthreshold, the example state detector 370 determines that the powervalue corresponds to an intermediate value. Accordingly, the examplestate detector 370 determines whether the previously logged state of theexample information presentation device 102 was in the OFF state (block1225). If the previous state of the information presentation device 102is the OFF state, the example state detector 370 determines the exampleinformation presentation device 102 in in the ON state (block 1227).

If the previous state of the example information presentation device 102is determined to be a state other than the OFF state, then the exampletimer 1078 of FIG. 10 initiates a delay period (block 1230). During thedelay period, the example state detector 370 monitors whether the valuesreceived from the example sensor 110 drop below the OFF threshold (block1235). If a power values drops below the OFF threshold during the delayperiod, the example state detector 370 determines the exampleinformation presentation device 102 is in the OFF state (block 1237).Additionally, in some examples, the example state detector 370 backcredits the example information presentation device 102 in the OFF statefor the period of time that the value received from the sensor 110 wasgreater than the OFF threshold. Otherwise, if the power values do notdrop below the OFF threshold during the delay period, the example statedetector 370 back credits the example information presentation device102 in the ON state for the time period corresponding to the duration ofthe delay period (block 1227). Additionally, the example state detector370 continues crediting the example information presentation device 102as in the ON state until the value received from the example sensor 110is less than the OFF threshold from the example threshold storage device394.

When the power state of the example information presentation device hasbeen determined (e.g., blocks 1217, 1227 and/or 1237), the example statedetector 370 stores the power state of the example informationpresentation device 102 in the example state ID storage device 396(block 1240). If the calibration period for the current iteration (e.g.,twenty-four hour period) has not expired (block 1245), control returnsto block 1210 and additional power values are received. Otherwise, ifthe calibration period for the current iteration has expired (block1245), the example calibrator 320 recalibrates the thresholds (block1250). The re-calibrations referred to at block 1250 are described indetail below in connection with FIG. 13. Control then returns to block1210.

The example of FIG. 13 begins with the example power logger 424receiving a value from the example sensor 110 of FIGS. 1 and/or 2 (block1305). The example running average calculator 426 calculates a runningaverage of the values received from the example sensor 110 over a periodof time (block 1310). Further, a list of power measurements (e.g., thelist 500 of FIG. 5A) is generated based on a comparison of the valuesreceived from the example sensor 110 and the calculated running average(block 1315). In particular, the list reflects power measurements withina percentage of the running average, and the power measurements notwithin the percentage are discarded and a previously logged powermeasurement is re-logged.

The example thresholds generator 440 generates a power chart (e.g., thepower chart 750 of FIG. 7B) based on the number of times a powermeasurement appeared in the power list relative to other powermeasurements (block 1320). The example thresholds generator 440identifies the two most frequently appearing power measurements in thepower chart (block 1325). The example thresholds generator 440identifies the lesser value of the two identified power measurements andsets the OFF state power measurement in accordance with the lesser value(block 1330). Further, the example thresholds generator 440 determineswhether the example calibrator 320 of FIG. 3 is in the learning mode(block 1335). If not in the learning mode (e.g., in the recalibrationmode), the example thresholds generator 440 sets the ON state powermeasurement by identifying the greater value of the two identified powermeasurements from the power chart (block 1337). Otherwise, if in thelearning mode (block 1335), the example thresholds generator 440calculates an ON state power measurement based off of the correspondingOFF state power measurement (block 1339). The example thresholdsgenerator 440 calculates an OFF threshold greater than the OFF statepower measurement and calculates an ON threshold less than the ON statepower measurement (block 1340). The example thresholds generator 440checks whether the OFF threshold differs from the ON threshold by aminimum percentage and outputs an indication indicative of the validityof the thresholds (e.g., ON and/or OFF) (block 1345). Based on thereceived validity indication, the calibrator 320 stores either the newthreshold values in the example threshold storage device 394 of FIG. 3(e.g., when the new threshold values are deemed valid at block 1345) orthe previous thresholds (e.g., when the new threshold values are deemedinvalid at block 1345) in the example threshold storage device 394 ofFIG. 3 (block 1350). Control then returns to block 1207 of FIG. 12 toenable the example state detector 370 of FIG. 3 to detect the state ofthe example information presentation device 102 based on the thresholdsstored in the example threshold storage device 394.

FIG. 14 illustrates a second example implementation of the example meter120 of FIG. 1. As described above in connection with the example meter120 of FIG. 3, the example meter 1420 is used to determine the powerstate (e.g., ON, OFF) of an information presentation device such as, forexample, the example information presentation device 102 of FIG. 1. Inaddition to the functionality described above in connection with theexample meter 120 of FIGS. 1 and/or 2, the example meter 1420 of FIG. 14monitors alternate indications that the example information presentationdevice 102 is in an ON state. For example, if audio data is beingdetected from the information presentation device 102, the informationpresentation device 102 is assumed to be in an ON power state.Monitoring alternate indications that the information presentationdevice 102 is in an ON power state is useful when, for example, theinformation presentation device 102 is considered to be in theindeterminate state (as described above in connection with FIGS. 10 and11). For example, rather than waiting the duration of the delay periodbefore determining the information presentation device 102 is in an ONpower state (e.g., during the time period between T7 and T9 in theexample graph of FIG. 11), detection of an alternate indication theinformation presentation device 102 is in an ON power state caninterrupt (e.g., terminate) the delay period and real-time statedetections of the information presentation device 102 can resume.Additionally, a new ON state power measurement and a new ON thresholdcan be calculated based on the received power measurement from theexample sensor 110 of FIGS. 1 and/or 2 when the alternate indication isreceived.

The example meter 1420 of FIG. 14 includes an example input interface301, an example calibrator 320, an example state detector 370, anexample chart storage device 392, an example threshold storage device394 and an example state ID storage device 396 that function similarlyto the counterpart components of the example meter 120 of FIGS. 1 and/or3. Because of the similarity of the like numbered components, thosecomponents from FIGS. 1 and/or 3 are not re-described here. Instead, theinterested reader is referred to the above description for a completedescription of those components. To monitor for alternate indications ofan ON state, the example meter 1420 of FIG. 14 includes an interruptdetector 1402 and one or more sensors 1405.

The example interrupt detector 1402 of FIG. 14 monitors alternate inputsto determine whether the example information presentation device 102 isin an ON power state. For example, the interrupt detector 1402 maymonitor whether audio data is being received from the exampleinformation presentation device 102 via the sensor(s) 1405. In someexamples, the sensor(s) 1405 monitor whether video data, digital videodata, digital audio data and/or data via a USB interface is beingreceived from the example information presentation device 102.Additionally and/or alternatively, the example sensor(s) 1405 maymonitor whether radio frequency (RF) and/or infrared (IF) data is beingreceived by the information presentation device 102 (e.g., from a remotecontrol). When the example interrupt detector 1402 of FIG. 14 determinesthe example information presentation device 102 is in an ON power statebased on the received alternate input via the example sensor(s) 1405,the example interrupt detector 1402 retrieves the power stateinformation from the state detector 370 of FIG. 14 as the power stateinformation is calculated as described above in connection with FIGS. 4and 6. When the power state information indicates the informationpresentation device 102 is in an indeterminate state, the interruptdetector 1402 outputs an interrupt indication to the example statedetector 370 of FIG. 14 and the example calibrator 320 of FIG. 14.

When the example state detector 370 of FIG. 14 receives an interruptindication from the example interrupt detector 1402, the example statedetector 370 interrupts the delay period initiated by the example timer1078 of FIG. 10. The example creditor 1082 receives the interruptindication from the example interrupt detector 1402 and outputs anindication that the information presentation device 102 is in an ONstate. In the illustrated example, the example state detector 370indicates an ON power state when it receives the interrupt indicatorfrom the example interrupt detector 1402 because the example interruptdetector 1402 received positive indication (e.g., audio data from theinformation presentation device 102, IR data from a remote control,etc.) from the example sensor(s) 1405 that the information presentationdevice 102 is in an ON power state. For example, as described above inconnection with the example graph 1100 of FIG. 11, while the statedetector 370 is operating in the indeterminate state (e.g., during thetime period between T7 and T9 in the example graph of FIG. 11), thestate detector 370 is waiting to see if the power drawn by theinformation presentation device 102 drops below the OFF threshold duringthe delay period or if the power measurement increases above the ONthreshold. However, if, while in the indeterminate state (e.g., duringthe time period between T7 and T9), audio data from the informationpresentation device 102 is received, the information presentation device102 is known to be in an ON state. This is because audio data would notbe received from the information presentation device 102 while in an OFFstate. As a result, the example state detector 370 does not need to waitfor the delay period to expire before determining the informationpresentation device 102 is in an ON state. In the illustrated example,the state detector 370 also resumes real-time state detection (e.g.,exits the delay period).

In the example of FIG. 14, when the example calibrator 320 receives theinterrupt indication from the example interrupt indicator 1402, theexample calibrator 320 interrupts the calibration period. As describedabove, the example interrupt detector 1402 outputs an interruptindication while the example state detector 370 is operating in theindeterminate state and when a positive indication that the informationpresentation device 102 is in an ON power state (e.g., audio datareceived from the information presentation device 102) is received fromthe example sensor(s) 1405. As a result of the received interruptindication, the example calibrator 320 determines the stored ONthreshold is incorrect because the information presentation device 102is in an ON power state while the power measurement received from theexample sensor 110 of FIGS. 1 and/or 2 is less than the ON threshold.The example calibrator 320 calculates a new ON state power measurementequal to the received power measurement from the example sensor 110 ofFIGS. 1 and/or 2 when the interrupt indication was received from theexample interrupt detector 1402. This calculation is valid because thereceived power measurement from the example sensor 110 is below the ONthreshold (e.g., the information presentation device 102 is in theindeterminate state), but the information presentation device 102 isknown to be in an ON power state (e.g., received interrupt indication).Thus, the ON state power measurement can be adjusted to match thereceived power measurement when the interrupt indication was received.

As described above in connection with the example ON thresholdcalculator 650 of FIG. 6, once the ON state power measurement is known,the example ON threshold calculator 650 calculates an ON threshold usinga graduated scale such as, for example, the scale represented in theexample table 900 of FIG. 9. This new ON threshold is then stored in theexample threshold storage device 394 and is used by the example statedetector 370 during state detection of the information presentationdevice 102 (e.g., real-time state detection). In the illustratedexample, the example time logger 422 of FIG. 4 also resets thecalibration period when the interrupt indication is received from theexample interrupt detector 1402. In other words, a new calibrationperiod (e.g., recalibration mode calibration period) is initiated.

While an example manner of implementing the meter 1420 of FIG. 1 hasbeen illustrated in FIG. 14, one or more of the elements, processes,and/or devices illustrated in FIG. 14 may be combined, divided,re-arranged, omitted, and/or implemented in any other way. Further, theexample calibrator 320, the example state detector 370, the exampleinterrupt detector 1402 and/or, more generally, the example meter 1420of FIG. 14 may be implemented by hardware, software, firmware and/or anycombination of hardware, software and/or firmware. Thus, for example,any of the example calibrator 320, the example state detector 370, theexample chart storage device 392, the example threshold storage device394, the example state ID storage device 396, the example interruptdetector 1402 and/or, more generally, the example meter 1420 of FIG. 14could be implemented by one or more circuit(s), programmableprocessor(s), application specific integrated circuit(s) (ASIC(s)),programmable logic device(s) (PLD(s)) and/or field programmable logicdevice(s) (FPLD(s)), etc. When any of the apparatus or system claims ofthis patent are read to cover a purely software and/or firmwareimplementation, at least one of the example calibrator 320, the examplestate detector 370, the example chart storage device 392, the examplethreshold storage device 394, the example state ID storage device 396,and/or the example interrupt detector 1402 are hereby expressly definedto include a tangible computer readable medium such as a memory, DVD,CD, Blu-ray, etc. storing the software and/or firmware. Further still,the example meter 1420 of FIG. 14 may include one or more elements,processes and/or devices in addition to, or instead of, thoseillustrated in FIG. 14, and/or may include more than one of any or allof the illustrated elements, processes and devices.

FIG. 15 is a flowchart representative of example machine readableinstructions that may be executed to implement the example meter of FIG.14. The example of FIG. 15 begins similar to the example of FIG. 12 withan activation of the example meter 1420 (block 1400). The correspondingblocks between FIGS. 12 and 15 are similar and were described above inconnection with the example of FIG. 12. Thus, a description of theblocks FIG. 15 and FIG. 12 have in common will not be repeated here. Theexample of FIG. 15 differs from the example of FIG. 12 in that itincludes a determination of whether an interrupt indication from theexample interrupt detector 1402 was received during the delay period(block 1532). If an interrupt indication from the example interruptdetector 1402 is not received by the example state detector 370 duringthe delay period, then the state detector 370 determines whether thedelay period expired (block 1534). When the delay period has expired,then the example process of FIG. 15 resumes the example process of FIG.12 at block 1235 and the example state detector 370 monitors whether thevalues received from the example sensor 110 drop below the OFF threshold(block 1235). Otherwise, if the delay period is not over, the examplestate detector 370 resumes monitoring whether an interrupt indicationwas received by the example interrupt detector 1402 (block 1532).

When an interrupt indication is received by the example state detector370 during the delay period (block 1532), the example state detector 370determines the example information presentation device 102 is in the ONstate (block 1547). When the power state of the example informationpresentation device has been determined (e.g., block 1547), the examplestate detector 370 stores the ON power state in the example state IDstorage device 396 (block 1549). Additionally, the example calibrator320 recalibrates the ON threshold (block 1551). As described above inconnection with the example calibrator 320 of FIG. 14, when an interruptindication from the example interrupt detector 1402 is received, a newON threshold is calculated based on the power measurement received fromthe example sensor 110 of FIGS. 1 and/or 2 at that time. Control thenreturns to block 1210.

FIG. 16 is a block diagram of an example processing platform 1600capable of executing the instructions of FIGS. 12 and 13 to implement,for example, the meter 120 of FIGS. 1 and/or 3. The processing platform1600 can be, for example, a server, a personal computer, an audiencemeasurement entity, an Internet appliance, a DVD player, a CD player, adigital video recorder, a Blu-ray player, a gaming console, a personalvideo recorder, a set top box, or any other type of computing device.

The processing platform 1600 of the instant example includes a processor1612. For example, the processor 1612 can be implemented by one or moremicroprocessors or controllers from any desired family or manufacturer.

The processor 1612 includes a local memory 1613 (e.g., a cache) and isin communication with a main memory including a volatile memory 1614 anda non-volatile memory 1616 via a bus 1618. The volatile memory 1614 maybe implemented by Synchronous Dynamic Random Access Memory (SDRAM),Dynamic Random Access Memory (DRAM), RAMBUS Dynamic Random Access Memory(RDRAM) and/or any other type of random access memory device. Thenon-volatile memory 1616 may be implemented by flash memory and/or anyother desired type of memory device. Access to the main memory 1614,1616 is controlled by a memory controller.

The processing platform 1600 also includes an interface circuit 1620.The interface circuit 1620 may be implemented by any type of interfacestandard, such as an Ethernet interface, a universal serial bus (USB),and/or a PCI express interface.

One or more input devices 1622 are connected to the interface circuit1620. The input device(s) 1622 permit a user to enter data and commandsinto the processor 1612. The input device(s) can be implemented by, forexample, a keyboard, a mouse, a touchscreen, a track-pad, a trackball,isopoint and/or a voice recognition system.

One or more output devices 1624 are also connected to the interfacecircuit 1620. The output devices 1624 can be implemented, for example,by display devices (e.g., a liquid crystal display, a cathode ray tubedisplay (CRT), a printer and/or speakers). The interface circuit 1620,thus, typically includes a graphics driver card.

The interface circuit 1620 also includes a communication device such asa modem or network interface card to facilitate exchange of data withexternal computers via a network 1626 (e.g., an Ethernet connection, adigital subscriber line (DSL), a telephone line, coaxial cable, acellular telephone system, etc.).

The processing platform 1600 also includes one or more mass storagedevices 1628 for storing software and data. Examples of such massstorage devices 1628 include floppy disk drives, hard drive disks,compact disk drives and digital versatile disk (DVD) drives. The massstorage device 1628 may implement the local storage device.

The coded instructions 1632 of FIGS. 12 and 13 may be stored in the massstorage device 1628, in the volatile memory 1614, in the non-volatilememory 1616, and/or on a removable storage medium such as a CD or DVD.

From the foregoing, it will be appreciated that disclosed methods,apparatus and articles of manufacture eliminate the need for manualcalibration of the thresholds (e.g., OFF threshold, ON threshold) usedduring state detection (e.g., OFF, ON) of an information presentationdevice. Furthermore, disclosed methods, apparatus and articles ofmanufacture adapt to new information presentation devices and improveaccuracy in state detection (e.g., OFF, ON) of the monitored informationpresentation device. Disclosed methods, apparatus and articles ofmanufacture recalibrate thresholds for information presentation devicesthat may change their power draw while in the OFF power state or cansignificantly decrease their power consumption while in the ON powerstate such as, for example, in an energy saver mode.

Although certain example methods, apparatus and articles of manufacturehave been described herein, the scope of coverage of this patent is notlimited thereto. On the contrary, this patent covers all methods,apparatus and articles of manufacture fairly falling within the scope ofthe claims of this patent.

What is claimed is:
 1. An apparatus to detect a power state of a device,comprising: a chart generator to determine respective counts for aplurality of measurements during a calibration period, the measurementsindicative of an amount of power drawn by the device, the countsindicating respective numbers of times the respective measurements weredetected; a calculator to determine a first threshold and a secondthreshold based on at least one of the counts, the first thresholddetermined using most frequently logged measurement values, the mostfrequently logged measurement values based on counts performed afterexpiration of the calibration period; a comparator to compare ameasurement to the first threshold and to the second threshold; and astate detector to store an indication that the device is in anindeterminate state if the measurement is greater than the firstthreshold and less than the second threshold.
 2. The apparatus of claim1, further including a checker to determine that the device is in an ONpower state when a previous power state is an OFF power state.
 3. Theapparatus of claim 1, further including a timer to initiate a delayperiod in response to the indication of the indeterminate state.
 4. Theapparatus of claim 3, wherein the comparator is to compare a pluralityof measurements to the first threshold during the delay period, and,further including a detector to, when at least one of the plurality ofmeasurements is less than the first threshold, identify the device is inan OFF power state.
 5. The apparatus of claim 4, wherein the detector isto interrupt the delay period in response to an indication that thedevice is in an ON power state during the delay period, the indicationto indicate that audio data was received from the device.
 6. Theapparatus of claim 4, further including a checker to determine that thedevice was in an OFF power state during the delay period if the deviceis identified in an OFF power state.
 7. The apparatus of claim 6,wherein the comparator is to compare a plurality of the measurements tothe first threshold during the delay period, and, when none of theplurality of measurements is less than the first threshold, the detectorto identify the device is in an ON power state.
 8. The apparatus ofclaim 6, wherein the checker is to determine that the device was in anON power when the detector determines that the device is in an ON powerstate.
 9. The apparatus of claim 6, wherein the checker is to determinethat the device is in an OFF power state when the detector determinesthat the measurement is less than the first threshold.
 10. A tangiblecomputer readable storage medium comprising instructions that, whenexecuted, cause a machine to at least: determine respective counts for aplurality of measurements during a calibration period, the measurementsindicative of an amount of power drawn by a device, the countsindicating respective numbers of times the respective measurements weredetected; determine a first threshold and a second threshold based on atleast one of the counts, the first threshold determined using mostfrequently logged measurement values, the most frequently loggedmeasurement values based on counts performed after expiration of thecalibration period; compare a measurement to the first threshold and tothe second threshold; and store an indication that the device is in anindeterminate state if the measurement is greater than the firstthreshold and less than the second threshold.
 11. The tangible computerreadable medium of claim 10, wherein the instructions, when executed,cause the machine to, when the device is in an indeterminate state:identify a previous power state associated with the device; and store anindication that the device is in an ON power state if the previous powerstate is an OFF power state.
 12. The tangible computer readable mediumof claim 10, wherein the instructions, when executed, cause the machineto, when the device is in the indeterminate state: initiate a delayperiod; compare a plurality of measurements to the first thresholdduring the delay period; and if at least one of the plurality ofmeasurements is less than the first threshold, identify the device is inan OFF power state.
 13. The tangible computer readable medium of claim12, wherein the instructions, when executed, cause the machine to, whenthe device is in an OFF power state during the indeterminate state:store an indication that the device was in the OFF power state duringthe delay period.
 14. The tangible computer readable medium of claim 12,wherein the instructions, when executed, cause the machine to identifythat the device is in the ON power state when none of the plurality ofmeasurements are less than the first threshold during the delay period.15. The tangible computer readable medium of claim 14, wherein theinstructions, when executed, cause the machine to: store an indicationthat the device was in the ON power state during the delay period whenthe device is in the ON power state during the indeterminate state;store an indication that the device is in an OFF power state if themeasurement is less than the first threshold; or store an indicationthat the device is in an ON power state if the measurement is greaterthan the second threshold.
 16. A method to detect a power state of adevice, the method comprising: determining, by executing an instructionwith a processor, respective counts for a plurality of measurementsduring a calibration period, the measurements indicative of an amount ofpower drawn by the device, the counts indicating respective numbers oftimes the respective measurements were detected; determining a firstthreshold and a second threshold based on at least one of the counts,the first threshold determined using most frequently logged measurementvalues, the most frequently logged measurement values based on countsperformed after expiration of the calibration period; comparing ameasurement to the first threshold and to the second threshold; andstoring an indication that the device is in an indeterminate state ifthe measurement is greater than the first threshold and less than thesecond threshold.
 17. The method of claim 16, further including, inresponse to the device being in the indeterminate state: identifying aprevious power state associated with the device; and storing anindication that the device is in an ON power state if the previous powerstate is an OFF power state.
 18. The method of claim 16, furtherincluding, in response to the device being in the indeterminate state:initiating a delay period; comparing a plurality of measurements to thefirst threshold during the delay period; and if at least one of theplurality of measurements is less than the first threshold, identifyingthat the device is in an OFF power state.
 19. The method of claim 18,further including, in response to the plurality of measurements beinggreater than the first threshold during the delay period: identifyingthat the device is in the ON power state; and storing an indication thatthe device was in the ON power state during the delay period.
 20. Themethod of claim 19, wherein the identifying of the device being in apower state during the indeterminate state includes: storing anindication that the device is in an OFF power state if the measurementis less than the first threshold; or storing an indication that thedevice is in an ON power state if the measurement is greater than thesecond threshold.